JUKES-BROWNE : ON SOME GENEKA OF VENEEID^. 243 



that so little is yet known about the animals of the numerous genera 

 and subgenera of the Veneridse. I cannot, indeed, find that anyone 

 has described the animal of any single species belonging to the groups 

 I have been dealing with. IJnder the head of ' Marcia,^ and con- 

 sequently referring inclusively to Samarangia, Katelysia, and Hemitapes, 

 Dr. Dall says " the soft parts appear to be unknown," It is therefore 

 with much pleasure that I am able to record some notes on the animals 

 of three different species belonging to the Marcia group. These are — 

 a specimen of Hemitapes variabilis (Phil.) sent me by Lieut. H. S. Brown 

 from the neighbourhood of Mangalore, south-west of India, and one 

 each of Katelysia scalarina (Lam.) and K. corrugata (Lam.), sent by 

 Dr. J. C. Yerco, of Adelaide, South Australia. 



Hemitapes variabilis (Phil.). Mantle widely open, with smooth 

 thickened margins, the medial lamina of which is slightly undulating 

 in the spirit-preserved specimen, but is not frilled, nor has it any 

 filaments at the anterior end. The siphons are very short, but are 

 entirely separate. The foot is deep and laterally compressed, but 

 elongate from anterior to posterior end, so as to be hatchet-shaped. 



The shell of this specimen belongs to the var. orientalis, Reeve. 

 I regard S. marmorata (auctorum, but ? Lam.), H. laterisulca (Lam.), 

 and H. ustulata (Desh.) as mere varieties of H. variabilis (Phil.). 



Katelysia scalarina (Lam.). The mantle of this has smooth margins. 

 The siphons are short, divergent, and separate, but united at the 

 base ; the lower one is thick, tough, and papillose at the end. The 

 foot is large, thick above, but compressed below, and elongated 

 anteriorly. 



Katelysia corrugata (Lam.). The mantle and foot as in K. scalarina. 

 The two siphons are better preserved in this specimen, are clearly quite 

 separate, though very short, and both the orifices are papillose. 



From the above descriptions it will be seen that all three species 

 agree in having smooth mantle-margins, short, separate siphons, 

 and a large compressed elongate foot. Consequently the inference 

 drawn from a study of the shells that they should be placed in the 

 same genus is confirmed by examination of the animals. 



As already stated, however, I think that Gomphina and Samarangia 

 are generically distinct from the Marcia-Katelysia group, and con- 

 sequently believe that three genera must be recognized. The following 

 are descriptive definitions of the genera and their subdivisions, so far 

 as the shells are concerned. 



Genus GOMPHINA, Morch, 1853. 



Generic characters. — Shell trigonal, rather thick, compressed, smooth, 

 or concentrically striated. Lunule long, narrow, superficial, and feebly 

 circumscribed ; escutcheon not defined ; ligament very short. Margins 

 of valves smooth ; dorsal margins of both valves grooved on both 

 sides of the hinge-plate to receive the opposing edges. Pallial sinus 

 small and rounded. 



Hinge-plate short, broad from the umbo inwards, triangular. Teeth, 

 three cardinals in each valve ; rather long, straight, separate, widely 

 and equally divergent. In the right valve the median is broad and 



