186 Transactions. 



and of which he knew no living representatives. These have since been 

 found, and in the British Museum is a fine series showing complete stages 

 of growth. This genus begins life as a normal Chlamys, and then settles 

 down and becomes an irregularly shaped Ostreiform bivalve. Fischer 

 (Man. de Conch., p. 945, 1886) has recorded this transformation. As 

 Chlamys has coincidently persisted as a free-swimming form, this proves 

 that Chlamys is very ancient, and is fully worthy of generic rank. The 

 close relationship of Chlamys and Hiioiites, two superficially different shells, 

 is proven, but no proof is yet forthcoming that Chlamys and Pecten, two 

 superficially similar forms, are as closely allied. 



Cyclopectev was provided for minute species with a peculiar facies which 

 are recognizable at sight, and their exact relationships seem somewhat 

 obscure. Why such a well-defined group which shows none of the charac- 

 teristics of the genus Pecten should be so classed is a problem I am quite 

 unable to solve. 



The nomenclature I would advocate reads, — 



Genus Pecten Miiller, 1776. 



Pecten medius Lamarck, 1819. 

 Genus Chlamys Bolten, 1798. 

 Chlamys dichrous (Suter, 1909). 



imparicostatus (Bavay, 1905). 

 radiatus (Button, 1873). 



- zelandiae (Gray. 1843). 



- convexus (Quoy and Gaimard. 1835). 



Genus Cyclopecten Vcrrill. 1897. 



Cyclopectev aviculoides (E. A. Smith, 1885). 

 transenna (Suter, 1913). 



In this arrangement 1 note I am in agreement with Hedley (Mem. Austr. 

 Mus.. iv, pp. 303 7, 1902). The reference of all the species to Pecten, as 

 Suter has done, would necessitate the rejection of two specific names, as 

 medius Lamarck, 1819, and radiatus Hutton, 1873, are antedated in the 

 genus Pecten (sensu latissimo), but not in my usage. 



Pecten gemmulatus (Reeve, 1852). [P. 878.] 

 This species is recognized as a subspecies of P. zelandiae Gray, 1843, 

 but it must be omitted. 



Mr. Edgar Smith. I.S.O., dealing with a Pecten from New Zealand, asked 

 me if I recognized it. I did not : but as he was getting the species together 

 I took the opportunity of examining the specimens. The types of Reeve's 

 Pecten gemmulatus at once attracted me by their strange appearance, and 

 it was soon decided that these were not Neozelanic, as far as we could 

 judge. Though Reeve gave the locality as " New Zealand, 1 ' the type-tablet 

 bears the original data t- Moreton Bay ; Strange." Nothing is here known 

 like them, and they disagree in detail with Suter's description of his sub- 

 specific form. 



Pecten multicostatus Reeve, included by Suter in the synonymy of 

 P. zelandiae Gray, must also be omitted, as it is not that shell, and the 

 locality " New Zealand " would appear to be incorrect. 



Genus Gaimardia (Gould, 1852). [P. 894.] 



This name, introduced in the U.S. Expl. Exped., vol. xii, p. 459, 1852, 

 for M. trapezina Lamarck, must replace Modiolarca Gray, 1847, not Modio- 



