Art. XLIII.—Additions to the Knowledge of the Recent Brachiopoda of New Zealand.
[Read before the Wellington Philosophical Society, 28th October, 1914.]
There are only four valid species of Brachiopod described from New Zealand waters—viz., Hemithyris nigricans (Sowerby), Neothyris lenticularis (Deshayes), Terebratella sanguinea (Leach), Terebratella rubicunda Sowerby. The occurrence of a fifth species, Crania sp. ind., has been indicated by Hutton* and Hamilton.† To this list I am now able to add four species, the locality of one of which is doubtful. Two species formerly included in Hutton's lists—viz., Magadina cumingi (Davidson) and Kraussina lamarckiana (Davidson)—are well-known Australian species, whose occurrence in New Zealand has not been verified during the last forty years, and they should be omitted from our lists.
Since the publication in 1887 of part ii of Davidson's “Monograph of Recent Brachiopoda”‡ no further study of the New Zealand forms has been made. Nevertheless, since that date observations of the greatest importance, affecting the whole classification, have been made on the South American forms,§ showing that the genera Magasella, Magas, Terebratella, and Magellania are related in such a way that the loops of the higher genera pass during growth through forms comparable with the adult loops of the lower genera. Beecher∥ has contrasted this series of growth stages with those of Macandrevia cranium and of some other northern species formerly assigned to Terebratella and Magellania, and, on account of the differences displayed, has founded for these species the genera Terebratalia and Dallina, placing them along with Macandrevia in a new subfamily, the Dallininae. Beecher rather hastily assumed that the Dallininae were entirely confined to the Northern Hemisphere and the Magellaninae to the Southern, and, this assumption being until recently unchallenged, it has not seemed a matter of urgency to study the growth stages of other species ascribed to the above-mentioned genera. Jackson,¶ however, has recently shown that a species of Macandrevia ranges from the Gulf of Panama to Coats Land, Antarctica, thus proving the occurrence of the Dallininae in the Southern Hemisphere. The occurrence of species of Magasella in the Northern Pacific has long been known, but their significance appears to have been overlooked. Elsewhere** I have shown that certain species of the Northern Pacific now generally ascribed to Terebratalia and Dallina have not the type of folding typical of members of that stock of the Dallininae, but that characteristic of the Magellaninae, and that on this account these species should probably be referred back to Terebratella†† and Magellania.
These circumstances in themselves make a study of the young stages of all Recent Brachiopods belonging to the Terebratellidae desirable, more
[Footnote] * Cat. Marine Mollusca N.Z. (1873), p. 87.
[Footnote] † Colonial Museum Bull. No. 1 (1906), p. 41.
[Footnote] ‡ Trans. Linn. Soc. Lond., ser. 2, Z ol., vol. 4, pt. i (1886), pt. ii (1887).
[Footnote] § P. Fischer and D.-P. Oehlert, Bull. Soc. Hist. nat. d'Autun, t. 5 (1892), pp. 254–334.
[Footnote] ∥ Trans. Conn. Acad. Arts Sci., vol. 9 (1895), pp. 376–99, pls. i–iii.
[Footnote] ¶ Trans. Roy. Soc. Edin., vol. 48 (1912), pp. 379–83.
[Footnote] ** Geol. Mag., dec. 6, vol. 2 (1915), pp. 71–76.
[Footnote] †† The genotype of Terebratalia come under this category, and if my contention is correct this genus becomes a synonym of Terebratella. I have proposed a new genus Dallinella as the Terebratelliform forerunner of Dallina
especially those of New Zealand, Australia, Japan, and western North America. When it is further recognized that within the Magellaninae, and probably also the Dallininae, there are different stocks that have arrived independently at similar loop forms, a knowledge of the growth stages becomes of the highest interest.
Young Stages of Terebratella rubicunda and Terebratella sanguinea.
Through the kindness of Miss Mestayer and Mr. H. Hamilton I have been able to examine a large number of the young of these species from Chetwode Islands (Cook Strait), Wellington Harbour, and Foveaux Strait. Specific discrimination is possible between these two species down to a length of 3 mm. for the ventral valve; the young of T. sanguinea is in general broader, and the multicostation has already commenced as a crinkling on the margins at that length. So far as the development of the loop is concerned, these two species agree almost entirely with T. dorsata, the development of which has been described by Fischer and Oehlert.* This is only to be expected, since the New Zealand species belong to Terebratella s. str, of which T. dorsata is the genotype.
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|Fischer and Oehlert.||Beecher.||Names adopted in this Paper.|
In the so-called Magadiform stage (fig. 5) the descending and ascending portions of the loop are separately attached to the septum, and the ascending portion forms a complete ring. This is the condition of the adult loop in Magadina browni, whereas in Magas pumilus the ascending branches, so far as is known, do not unite to form a ring. Moreover, in the growth of the loop of Terebratella the ascending portion never passes through a stage where the ring is incomplete. It is therefore desirable to replace the term “Magadiform” by “Magadiniform.” Similarly the term “Magaselliform” has not been used in an unequivocal sense. It is restricted by Fischer and Oehlert and Beecher to the stage, later than Magadiniform, where the descending and ascending portions of the loop have united with one another along the side of the septum (fig. 6). This is the stage attained in the adult loop of Magella carinata, but many species classed under Magasella have not passed the Magadiniform stage. Hence it will conduce to clearness if the term “Magelliform” be used for the later stage, and the term “Magaselliform” be used in a wider sense for both Magadiniform and Magelliform stages—that is, for shells with a high septum rapidly lessening in height posteriorly, and with descending portions of
[Footnote] * Loc. cit.
the loop complete. For the earliest stages with a high septum and with the descending portions of the loop incomplete the term “pre-Magadiniform” may be used.
Beecher has compared the pre-Magadiniform stages with the adult condition of the loop in Bouchardia and Megerlina, but there are important differences which make the use of the terms “Bouchardiform” and
Fig. 1.—Terebratella rubicunda, Chetwode Islands. Pre-Magadiniform stage, before the appearance of the hood on the septum. Length of ventral valve, 3 mm.
Fig. 2.—Terebratella rubicunda, Chetwode Islands. Pre-Magadiniform stage, with small hood on septum. Length of ventral valve, 3.5 mm.
“Megerliniform” misleading. In each of these genera, as in Magas, the ascending branches do not unite to form a ring, while in B. rosea the descending branches are completely absent. In the young stages of Terebratella there is never an incomplete ring, while the growth of the descending branches commences before any indication of the ascending branch can be found on the septum. It is probable that in loop characters B. rosea is degenerate from a stock originally possessing pre-Magadiniform characters. The loops of the fossil species of Bouchardia are as yet unknown, and their description will possess the highest interest.
In the young of Terebratella rubicunda there is a great deal of latitude in the relations between size of shells and stage of loop-development attained. Generally speaking, the Magadiniform characters are attained at a length
Fig. 3.—Terebratella rubicunda, Chetwode Islands. Pre-Magadiniform stage, with ring developed from hood. Length of ventral valve, 3.5 mm.
Fig. 4.—Terebratella rubicunda, Foveaux Strait. Late pre-Magadiniform stage, retaining a hood on the septum when the descending branches are nearly complete. Length of ventral valve, 6 mm.
of 4 mm., but one specimen of 6 mm. is still in the pre-Magadiniform stage. Magelliform characters usually commence at a length of 6 mm., and are quickly superseded by early Terebratelliform characters.
The only observations I have been able to make on loop-development additional to those of Fischer and Oehlert relate to the very early stages. The growth of the crura commences, as they have pointed out, before any
sign of the ring appears on the septum (fig. 1). I have observed several specimens in a succeeding stage in which a very small hood, not a ring, appears on the posterior end of the septum (fig. 2). The base of this hood later becomes resorbed, and it passes into a ring (fig. 3), but sometimes it persists to a fair size (fig. 4). In the large specimen of 6 mm. previously mentioned, the front parts of the descending branches have already appeared on the septum before the hood has developed into a ring.
Fischer and Oehlert made no observations on the development of the hinge-plate, which is a characteristic of the Terebratella-Magellania stock. In their figures of T. dorsata the septum does not extend back as far as the hinge-plate until the Magelliform stage is reached, whereas in T. rubicunda it passes under the anterior end of the hinge-plate in the Magadiniform, and exceptionally in the pre-Magadiniform, stage. The development of the hinge-plate commences independently of the septum. In very young specimens it starts as two almost vertical plates on the inner sides of the anterior end of the socket-ridges, separated in front from the socket-ridges by a hollow, but behind coalescing with them. Possibly these two plates
Fig. 5.—Terebratella rubicunda, Foveaux Strait. Early Magadiniform stage. Length of ventral valve, 4 mm.
Fig. 6.—Terebratella rubicunda, Foveaux Strait. Magelliform stage. Length of ventral valve, 8 mm.
are united along the middle line of the valve, but, if so, they are closely applied to the bottom of the valve. In succeeding stages these plates descend from the socket-ridges more and more obliquely, thus gradually approaching one another, while the hollow between them and the floor of the valve gradually increases in size. In later Magadiniform stages, where the septum now reaches back to the region of the hinge, these plates unite above the septum, but farther back they are still applied to the bottom of the valve. Finally, in the Magelliform stages the septum reaches right back under the hinge-plates to the umbo, and the characteristic Terebratelliform hinge characters are attained. The cardinal process appears at the umbo in very early stages in much the same form as it attains at maturity, while the hinge-teeth of the ventral valve are also well developed in the early stages.
The ridge separating the muscular markings of the ventral valve, which is situated anteriorly in Bouchardia and Magadina, but posteriorly in Terebratella and Magellania, is well developed in the young stages of T. rubicunda, and is situated anteriorly in pre-Magadiniform stages, centrally in the Magadiniform stages, and posteriorly in the higher stages.
The young stages of Terebratella sanguinea differ in no important respect from those of T. rubicunda.
Young Stages of Neothyris lenticularis.
It is known from the observations and figures of Douvillé* and Davidson† that the loop of this species passes through Magelliform and Terebratelliform stages during growth, and it is probable that the still earlier stages do not differ from those of Terebratella. Unfortunately, I have not yet been able to obtain a series of very young shells in which to confirm this, though such a series should not be difficult to obtain from the oyster-dredges of Foveaux Strait. The study of the development of the cardinal process in this species will be of much interest.
Additions to the List of Species occurring in the New Zealand Area.
Liothyrina sp. ind. Fig. 8.
Included in Mr. Hamilton's collection from Foveaux Strait there is a single example of Liothyrina. This genus is characterized by a short Terebratuloid loop, a thin shell finely punctate, and the presence of 4 radiating furrows in the interior of the dorsal valve for the attachment of the pallial sinuses, all of which characters are well displayed by the present example.
Fig. 8.—Liothyrina sp., Foveaux Strait. a, dorsal view; b, side view; c, interior of dorsal valve. Length, 14 mm.
In shape it is suborbicular, and entirely non-plicate, and has all the appearance of a young shell, for which reason I do not propose to give it a specific name at present. The beak characters are hardly typical of Liothyrina, which usually has at least slight anterior projection of the lip of the foramen; but, again, this may be due to its youth.
Liothyrina occurs in both the Northern and Southern Hemispheres, but has not been before recorded in the New Zealand - Australian area. It is known from the English chalk, and probably occurs in the Italian Tertiaries, but none of the New Zealand or Australian Tertiary Terebratuloids, though in some cases thin-shelled, appear to belong here. It appears, therefore, to be a recent immigrant to our waters, in contradistinction to our other species, which are all descendants of known Tertiary shells.
Neothyris ovalis (Hutton). Fig. 9.
1886. Waldheima ovalis Hutton, Trans. N.Z. Inst., vol. 18, p. 335.
1905. Magellania lenticularis ovalis Hutton, Trans. N.Z. Inst., vol. 37, p. 475, pl. xlv, fig. 2.
This species is related to N. lenticularis, but differs in shape and also in its less incurved beak and much larger foramen, while the cardinal process is also more primitive. It is abundant in the younger Tertiary
[Footnote] * Bull. Soc. Geol. Fr., ser. 3, t, 7 (1879), p. 256, fig. 3.
[Footnote] † Loc. cit., pt. i, pl. 9., figs. 11, 12, 13.
rocks (Wanganuian) of the North Island, but has not hitherto been found Recent. The specimen here figured was obtained by Captain Bollons from Farewell Spit. The colour is pinkish-red, as in N. lenticularis, and the shell is sufficiently translucent for the pallial sinuses to show through.
It is rather remarkable that Neothyris campbellica Filhol, which is intermediate in characters between N. ovalis and N. lenticularis, should not also be found Recent. It is a common Wanganuian fossil in the North Island and on Campbell Island.
Terebratella sp. cf. Magella carinata Thomson.
In Mr. Hamilton's collection there are four specimens from Foveaux Strait of a new species of Terebratella, which differ from T. rubicunda by the possession of a more pronounced ventral unicarination, of an incomplete foramen, and of distinctive colour-markings. The shell is of a pale pinkish-white colour, with irregular radial splashing of deep red. Such colour-markings are rare amongst Recent Brachiopods, but occur in Bouchardia rosea. In shape the adult shells agree nearly with Magella carinata, but the loop has advanced to an early Terebratelliform stage. The four specimens comprise two adults, about the size of small specimens of T. rubicunda, and two half-grown shells, not so carinate, and with Magaselliform septa. Unfortunately, the two adults are too damaged to serve as type specimens, and in consequence it is better to leave the species unnamed at present.
It is remarkable that this species, undoubtedly a descendant of the Oamaruian Magella carinata, should not be found in the Wanganuian rocks. The explanation may be that it has always been restricted to a southern habitat. Magella carinata has only been found near Oamaru, and the present species occurs in Foveaux Strait, still farther south, while no Wanganuian marine rocks are known from Otago or South Canterbury.
Magellania flavescens (Lamarck).
There is in Miss M. Mestayer's collection a single specimen of this species, which probably comes from the Chatham Islands. It was in a box of Hemithyris nigricans labelled “Chatham Islands and Lyall Bay,” and, since the Lyall Bay habitat has not been confirmed, the probability is that it came from the Chatham Islands. Miss Mestayer is positive that it did not come from Australia. Nevertheless, its occurrence must be verified before it can be added to our list.
The shell is a rather elongate form, with strong ventral uniplication and little sign of biplication, and the multicostation is perhaps a little finer than usual. Nevertheless, it comes well within the range of variation figured by Davidson.