distribution? This cannot be convincingly answered until we find out more about the life histories of the different species, and, given favourable currents and water temperatures, what distance of ocean they could cross. Records of a species from two faunal regions should be examined in the light of a possible convergence; but in a family like the Veneridae, convergence is probably uncommon because so many coincidences are involved; such as do occur will be found among genera with a simple sculpture.

Parallelism, or the development of two related stocks along similar lines may explain many of the resemblances which have been noted betwen New Zealand shells and those of other regions; but this explanation only puts the common origin a little earlier in time; it does not do away with the need of explaining how the two stocks acquired their present distribution.

The following is a rough outline of the history and affinities of Venerid genera that have been collected recent and fossil in New Zealand.

In its broad sense, Dosinia has existed in New Zealand waters throughout the Tertiary, and though no true representatives have been recorded from our Cretaceous, they will probably yet be found. Dosinia does not occur in the Northern Hemisphere until the Aquitanian, i.e., Lower Miocene, so von Ihering's statement that the subfamily originated in an Antarctic continent of Upper Cretaceous times and spread from there northwards in the Tertiary is very likely correct. Several of the subgenera such as Austrodosinia, Raina, &c. seem to have originated in New Zealand; but the writer has not had access to Australian or South American specimens for detailed comparisons. Tate (1887, p. 161) recorded Dosinia greyi from Edithburgh, St. Vincent Gulf, and although the specific identity might not now be upheld, it is possible that the shell is a Kereia. Phacosoma is a Japanese subgenus of which the earliest known occurrence in New Zealand is from the Lower Pliocene of Wanganui district.

The new genus Finlaya, from the Wangaloa beds, appears to be related to Dosiniopsis, founded on an Eocene fossil from the Eastern United States. Dosiniopsis occurs also in the Eocene of the Paris and London Basins and (fide Jukes-Browne) in the Upper Cretaceous of England. Obviously the distribution must have been very much wider and remains to be revealed, or we have a remarkable case of convergence combined with coincidence in time. The Wangaloa Beds from which the New Zealand species comes are probably Paleocene.

Upper Cretaceous rocks of almost every country furnish shells of the Callistina group. Therefore it is not surprising to find a close relative in Tikia which probably came to these shores from the northwest.

Paradione occurs typically in the Parisian Eocene, but similar shells are wide spread throughout the Tertiary. The New Zealand and Australian members are regularly finely striated, as in the young Paradione, so they probably branched off at a somewhat earlier stage than is represented by the adult type species. For these southern forms Iredale has proposed the genus Notocallista, which is here given only subgeneric rank.

Hyphantosoma: Apart from the unusual sculpture the New Zealand shell agrees closely in shape and details of hinge with the typical Jamaican ones. Perhaps Hyphantosoma reached our shores along with Chione and Protothaca.

Marama, Hina, Kuia, and Dosinula belong to the Antigona group of genera, the distribution of which is difficult to ascertain because these shells are often classed as Chione, and many authors do not figure the hinge. They are certainly widely spread in present Indo-Pacific and European seas and have been recorded from the Tertiary of a still wider area. The foreign genus most closely resembling the New Zealand genera is Ventricoloidea which appears first in the Oligocene of Europe, but the evidence we have is insufficient to show the connexion between them.

Bassina occurs in the Recent seas of New Zealand, Tasmania, and south-eastern and southern Australia. It has been found in the Lower Pliocene of Victoria and South Australia and in the Lower Miocene (and probably the Oligocene) of New Zealand.

The New Zealand example of Clausinella, C. morgani, is by no means typical. Its sculpture and shape are the same as those of C. thiara (Dillwyn) from the Philippines and Queensland. The hinge, however, is more arched, and the teeth are shorter than in C. fasciata the genotype, and the lunule, as in C. thiara, is bounded by a groove. The young thiara and morgani have distant thin concentric lamellae like Bassina calophylla (Philippi), but the young fasciata is almost smooth with fine concentric grooves resembling Chamelea. Judging from the sculpture and the incised lunule the New Zealand fossil and C. thiara are more closely related to each other than to C. fasciata, but the hinge of C. thiara agrees with that of fasciata while morgani is slightly different.

The exact relationships, however, cannot yet be made out. C. fasciata has no well-defined ancestral line in the Tertiary of Europe and may be a recent arrival there. C. dertoparva Sacco from the Miocene was cited by Jukes-Browne as an ancestor, but it has an anterior lateral tubercle and so belongs rather to Artena.

Tawera is common in New Zealand, the south-eastern part of Australia, Tasmania, Chatham Islands, Auckland Island, and Macquarie Island. Von Ihering (1907, p. 297) stated that Chione gayi Hupé from Magellan Straits and Chile is “intimmement relationee à la Ch. mesodesma Q. & G. de la Nouvelle Zelande” and Smith (1885, p. 131) identified as C. mesodesma, a shell dredged from Station 135E 1000 fathoms, off Tristan da Cunha. This last record, however, is surely a mistake; for the genus elsewhere is a shallow-water one. It is incredible that the New Zealand species should occur at 1000 fathoms in the Atlantic when its home is under the 50-fathom mark in New Zealand.

Early fossil occurrences of the genus are Tawera propinqua (Tate) from the Balcombian (Oligocene) and T. marshalli from the Awamoan (about Lower Miocene) of Target Gully.

The small shells which have here been given the name Turia may form a connecting link between Kuia and Marama on the one hand and Tawera on the other, for the left anterior cardinal is intermediate

in the degree of its forward extension. If this is so the process seems to have been one of a reduction of the anterior lateral tooth, for Marama and Turia first occur much earlier than Tawera.

Austrovenus possesses so much in common with species of Chione s. str. from the West Indies, Central America and California that there can be no doubt that they owe this to a common origin. The stocks of each region have probably not had any connexion for a very long period, because several of the chief characters of A. stutchburyi are distributed over a number of American species. Chione has existed in the West Indian—Californian area since the Oligocene but the earliest known Austrovenus appears in the New Zealand Pliocene. The related A. (Hinemoana) acuminata (Hutton) from brackish-water beds in Otago, of perhaps Oligocene age, has a posterior lateral tooth and very fine concentric ornamentation, so that it is probably an offshoot from the main line of descent. It shows, however, that relatives of Chione and Austrovenus were living in New Zealand waters early in the Tertiary.

Eumarcia and Atamarcia have close relatives in Australia and in South America, and have probably been in these areas and in New Zealand since Cretaceous times.

The name Cyclorismina has been introduced for an Upper Senonian fossil from Selwyn Rapids which resembles Cyclorisma oldhamiana Stoliczka-from the Trichinopoly group of India.

The new subgenus Gomphinella is found in the Pliocene and Recent of Japan and New Zealand, and the genus Gomphina sensu lato in Australian Recent seas as well.

Protothaca is distributed along the western coasts of South and North America in Japan and New Zealand. The species from our seas has been separated as a subgenus, Tuangia, because of its shape and coarse culpture, but we know nothing of its Tertiary history. The only fossil occurrence in New Zealand so far recognized is from a raised beach apparently of Pleistocene age. Concerning the genus von Ihering (1907, p. 296) said “Protothaca, au contraire est un élément charactéristic de la faune eogène de la Patagonie, et du Chile, d'où elle s'est répandue jusqu'à la Californie pendant la formation Miocène.”

Paphirus, Irona, and Notopahia have relatives in Ruditapes, Pullastra and Venerupis. These genera are found in the regions to the north-west and west of New Zealand, i.e., the Indo-Pacific, the Australian and the European. Irona and Notopaphia have not yet been found earlier than the Pleistocene but Paphirus is common in the Upper and Middle Pliocene.

From the foregoing it will be seen that the evidence does not support the idea that the Veneridae of New Zealand have been isolated since Cretaceous times and that the late Tertiary and Recent species have been derived directly and solely from the Cretaceous fauna of this region. Indeed the fact that the whole subfamily of the Venerinae is known only from the Tertiary and is so well represented in New Zealand seems to prove that important migrations reached these shores (or left them) after the close of the Cretaceous. The stratigraphical occurrence, as far as known, of the different genera, is shown in table 1.