58 



A SYNOPSIS OF THE FAMILY VENEEID^. PAUT I. 



By A. J. Jdkes-Browne, F.H.S., F.G.S. 



Read 12th December, 1913. 



During tlie course of the past eight years I have collected and studied 

 the members of this family, both recent and fossil, and the results of 

 my studies of some of the generic groups have been communicated 

 to this Society from time to time. I have now prepared a general 

 synopsis of the whole family in order to record my final views on the 

 affinities and taxonomic values of the numerous groups, generic and 

 sub-generic, which have been recognized by different writers at 

 various times. 



The family is a large one, and has generally been divided into three 

 or four tribes or sub-families. Thus Deshayes, in 1853, made four 

 such divisions which he called Dosiniana, Meretriciana, Venusina, and 

 Tapesina.' Fischer, in 1887,- only recognized three such tribes, 

 viz. Meretricinse, Venerinse, and Tapetinae ; but Dr. Dall, in 1902, 

 again proposed to make four sub-families, viz. Dosiniuge, Meretricinae, 

 Venerinse, and Gemminae. He rightly considered that the distinction 

 between Venerinae and Tapetinae could not be maintained; but in my 

 opinion the same must be said of the supposed distinction between 

 Dosininae and Meretricinae, for the difference between the shells of 

 Dosinia and Pitaria is very small, and there is probably quite as little 

 difference between the animals. The two genera are linked together 

 by the sub-genera which have been described by M. Cossmann and 

 myself under the names of Sinodia and Cordiopsis. 



With respect to the Geramina^, they are separated by Dr. Dall 

 because their embryos are incubated by retention within the mantle- 

 cavity, as in the case of Sphcurmm and Pisidium. He calls this 

 viviparous reproduction, but the term is hardlv correct, for, as 

 Professor Pelseneer has remarked, "there are no viviparous Lamelli- 

 branchs, though a certain number of them appear to be so because 

 they are incubators." The fact that Gemma, Parastarte, and Psephidia 

 protect their young in this way is interesting, but it does not follow 

 that they are closely related in other respects, and we know so little 

 about the developmental arrangements of other genera that it seems 

 unnecessary at present to separate these groups from those which 

 seem to be their nearest allies. For instance, the shell of Psephidia 

 closely resembles that of Gomphina, and it is quite possible that 

 Gomphina incubates its embryos : we simply do not know. Con- 

 sequently I do not propose to recognize the Geynmince as a distinct 

 sub-family, believing that it is at present not convenient to make 

 more than two such divisions, viz. the Meretricinae and the Venerinae. 



I had hoped that the nomenclature of the various genera and sub- 

 genera would have been settled before I set myself to draw up this 



^ Catalogue of the Conchifera in the British Museum, London, 1853. 

 2 P. Fischer, Man. de Conch., Paris, 1887. 



