Art.. XXVI.—Notes on some Foraminifera, from the Hauraki Gulf.
[Read before the Auckland Institute, 21st February, 1887.]
During my first visit to Auckland, I took the opportunity of collecting and examining large quantities of sand and mud along the shores of the Hauraki Gulf, which proved to be very rich in Foraminifera and other minute organisms. The material was taken at low water in creeks and pools, and on the sandy beaches, and washed in the ordinary simple way, by which a fairly pure residuum of Foraminifera, Diatoms, Crustaceans, Polyzoa, etc., was obtained.
After my return from the King Country, I hope to be able to devote some time to the study of the Rhizopoda, and to give a detailed description of the numerous varieties, with illustrations of the principal types, a list of synonyms, and tables of geological and geographical distribution. In this short paper, I merely intend to give a general idea of the rhizopodal fauna from the littoral zone, and a list of species or types. The slides containing the enumerated forms will be left at the Auckland Museum.
The general appearance of these washings remains very uniform. The characteristic features are the extraordinary abundance of the porcellaneous and some of the higher vitreous types, the scarcity of arenaceous and the lower vitreous forms. The Miliolidœ form over 90 per cent. of the whole fauna, as in various other shore-gatherings from the northern seas. The only new varieties belong, as far as I can judge, to this extensive group, but it is not unlikely that other forms new to science will be found after further researches, especially in the shallow creeks facing the open sea. With the exception of these varieties, all the species found near Auckland occur in the same cathymetrical zone of almost every latitude,
and in many tertiary and even older formations of Europe. The specimens are, as a rule, of good size, and even the most delicate tests remarkably well preserved. They can easily be picked out with an ordinary pocket-lens, and examined with a 1-inch objective.
In the porcellaneous group, the genus Miliolina is best represented, while the allied genera, Nubecularia, Biloculina, and Spiroloculina occur only in isolated individuals. Ribbed and otherwise ornamented species are exceedingly rare. The Miliolines are very variable, and run so gradually into each other that no distinct lines of demarcation can be drawn. Monstrous specimens are frequent, and difficult to determine.
The second large group is almost entirely absent. It is evidently in deeper water that we must look for arenaceous forms of the families Astrorhizidœ, Lituolidœ and Textularidœ. The most interesting species from these shores is Thurammina papillata, of which one of the slides contains two small spherical specimens.
The Lagenidœ, belonging to the third group (Hyalinea), are also exceedingly rare. The most beautiful, delicately ornamented, Lagena squamosa is the most abundant. The higher rotaline forms are well represented, and belong to geographically widely diffused types.
1. Gen. Nubecularia.
No good specimen, but small fragments of a variety of N. lucifuga, Defr.
2. Gen. Biloculina.
Rare specimens of B. ringens, Lam.
3. Gen. Miliolina.
With the typical forms, numerous abnormally developed shells were obtained, which can be considered as intermediate forms between the quinqualoculine and triloculine Miliolinœ and the symmetrical Biloculinœ and Spiroloculinœ, and the different dimorphous groups.
It is an easy task to construct long series which show almost every conceivable deviation with regard to general form, arrangement and relative size of chambers, shape and position of the aperture, and colour, which prove clearly how little value we have to attribute to morphological characters, which are often considered of greatest importance for the systematical arrangement of species, and even whole genera. Some specimens are almost symmetrical, others show different modes of growth at different ages. Frequently the final chamber does not follow the general plan of growth. A careful comparison of numerous specimens is necessary to ascertain the relationship between the widely different modifications of the simplest types.
Innumerable mutations of the following species are met with:—Miliolina circularis, Born.; M. seminulum, Lin.; M. oblonga, Mont.; M. labiosa, D'Orb.; M. secans, D'Orb.; M. bicornis, W. and T.; M. linnœana, D'Orb. To which we can add, as distinct varieties:—M. aucklandica and M. polymorpha.
4. Gen. Spiroloculina.
Small specimens, occupying an intermediate place between Miliolina (Quinqueloculina) and Spiroloculina.
5. Gen. Rhabdammina.
Fragments of monothalamous arenaceous tubes, belonging, probably, to a large species of the Astrorhizidœ group (var. of Rh. abyssorum?).
6. Gen. Reophax.
Irregular, dentaline modifications of R. scorpiurus, Mont., with dark grey, calcareous cement.
7. Gen. Haplophragmium.
Small, finely arenaceous, colourless, and ochreous forms of H. canariense, D'Orb., and H. globigeriniforme, P. and T., similar to those found in the North Atlantic and in some mesozoic strata (zone of Ammonites transversarius, etc.).
8. Gen. Thurammina.
Delicate, spherical tests of Th. papillata, Brady, with short papillæ distributed regularly all over the surface, resembling the passage forms of Th. albicans and Th. papillata from the upper jurassic strata.
9. Gen. Valvulina.
Finely arenaceous, much compressed specimens of V. conica, P. and T., almost isomorphous with Trochammina squamata.
10. Gen. Bolivina.
Very rare, delicate, glassy modifications of B. punctata, D'Orb.
11. Gen. Lagena.
Four species of the groups Lœvigatœ and Reticulatœ. The absence of the cosmopolitan L. globosa, L. lœvis, L. marginata, and L. sulcata, so common in British littoral deposits, is a curious fact.
12. Gen. Globigerina.
Small ash-grey specimens of G. bulloides, D'Orb.
13. Gen. Patellina.
Two young shells of P. corrugata, Will.
14. Gen. Discorbina.
This group is well represented along the whole coast, and numerous fine specimens were obtained, the largest near the pier of North Shore. When the surface is much worn, or the aperture filled up or damaged, it is difficult to distinguish them from the other rotaline forms with which they are always associated. The following species were recognized:—D. rosacea, D'Orb.; D. turbo, D'Orb.; D. globularis, D'Orb.; D. valvulata, D'Orb.; D. orbicularis, Terq.
15. Gen. Truncatulina.
A few doubtful specimens, probably of T. lobatula, were found at Cheltenham Beach.
16. Gen. Carpenteria?
A single fragment from the same locality appears to belong to this curious group.
Fine large specimens of Pulv. repanda, F. and M., are frequently met with; also, P. elegans, D'Orb.
18. Gen. Rotalia.
Two distinct varieties, of very different size, of the common R. beccarii.
Numerous beautiful tests of at least three species are found everywhere—N. depressula, W. and T.; N. scapha, F. and M.; N. asterisans, F. and M.?
20. Gen. Polystomella.
Several varieties of these beautifully-marked forms were obtained. They belong to P. striatopunctata, F. and M.; P. crispa, Lin.; P. macella, F. and M.
List of Species.
Nubecularia, lucifuga, Defr., v.r.
Biloculina ringens, Lam., v.r.
Miliolina circularis, Born., r.
M. seminulum, Lin., v.c.
M. oblonga, Mont., v.c.
M. labiosa, D'Orb, c.r.
M. secans, D'Orb., c.r.
M. bicornis, W. and T., v.r.
M. linnœana, D'Orb., r.
M. aucklandica, sp. nov.
M. polymorpha, sp. nov.
Spiroloculina, sp. ind.
Rhabdammina abyssorum, Sass.
Reophax scorpiurus, Mont.
Haplophragmium canariense, D'Orb.
H. globigeriniforme, P. and T.
Thurammina papillata, Brady.
Valvulina conica, P. and T.
Bolivina punctata, D'Orb.
Lagena apiculata, Reuss.
L. squamosa, Mont.
L. hexagona, Will.
L. striatopunctata, P. and T.?
Globigerina bulloides, D'Orb.
Patellina corrugata, Will.
Discorbina rosacea, D'Orb.
D. turbo, D'Orb. (?)
D. globularis, D'Orb.
D. valvulata, D'Orb.
D. orbicularis, Terq.
Truncatulina lobatula, W. and T.
Pulvinulina repanda, F. and M.
P. elegans, D'Orb.
Rotalia beccarii, Lin.
Nonionina depressula, W. and T.
N. scapha, F. and M.
N. asterisans, W. and T.
Polystomella striatopunctata, F. and M.
P. crispa, Lin.
P. macella, F. and M.