OF SOUTHERN INDIA. 183 



XV. Famllu,— GLOSSID^.'' 



All the animals referable to this family have an oval or elongately oval shape, 

 heiug stout and tliiek ; the mantle has a very lai'ge opening ventrally in front for the 

 protrusion of the foot, and another large gape behind for the sijihons, the margins 

 being united only for a short distance between both openings. The siphons are 

 separated, short, and with fringed orifices ; the foot is somewhat compressed, more 

 or less conical and pointed at the end, a byssal groove occurs sometimes on the 

 lower side, but the byssus itself is very rarely developed ; the gills are large, 

 unequal or sub-equal, the palpi long and narrow, the retractile muscles very 

 strong. 



The shells are sometimes elongated, but mostly of an oval inflated form, solid ; 

 the hinge provided with two or three cardinal and one posterior lateral tooth, some 

 slight modification occurring in both ; the pallial line is entire or very slightly 

 sinuated (in CoraUioplwga), and the ligament is external. 



H. and A. Adams have divided the shells which here form the family 

 Glossidm into three families. The question, however, as to the relation of Ci/prina^ 

 i'rcipezium f=C>jpricardlaJ, and Glossus f = BucarcUa ov Jsoca?'(ZiaJ has been 

 lately so fully discussed l)y Deshayes in his 2nd edition of the Paris fossils that I 

 can be brief on this subject. Deshayes includes those three generic groups with 

 Canlium in one family, but comparing carefully the shells and animals with those 

 of true Cardia, there is, I think, sufTicicnt reason to treat them sepai-ately in distinct 

 families. The animals of the Glossidje certainly greatly resemble those of the 

 Cteesidje, but those of the Caudiid.e show in the form of the foot the crenulations 

 of the mantle margins, and in the arrangement of the hinge-teeth considerable 

 differences, as I had already mentioned when speaking generally of the order 

 VENEBACEA, and as I shall again point out when I come to speak about the 

 Cardiidm; I think the distinctions warrant the separation of the two families. 



On the other hand, I entirely agree with Deshayes as to his classification 

 of the genus Trapezium (= CijpricardiaJ, which H. and A. Adams place in the 

 TAPESiN^. There can, I believe, be no doubt that a very gradual transition in the 

 form and arrangement of the hinge-teeth can be traced from one genus into the 

 other, and the same applies to the form of the shell itself. Tlius, for instance, we 

 have in Callocardia apparently the Venoroid type without any posterior lateral 

 teeth. Glossocanlia has the form of Trapezium, but the arrangement of the 

 hinge-teeth is similar to that of Glossus. The various forms of the fossil genus 

 Veniella again exhibit a gradual transition from the hinge of the Glossus-tj-pe to 

 that of Cyprina, so much so that in some instances, as those referring to Veniella 

 proper and also to Veuilicardia, great difficulty is experienced in drawing a line 

 between the two. Further details on this point will be seen from a comparison 

 of the characteristics of the various genera. Besides various fossil species of which 



* The name CrpmyiD^ ma}- lie more appropriate and would have priority, l.iut it has already long a^o been used 

 in Ichthyology. 



