88 VliOCEEDINGS OF THE JIALACOLOGICAL SUCIETV. 



all under Tapes. It was Dr. Dull in 1902 wlio tirst proposed to 

 separate this assemblage as a genus under the name of JIarcia, but lie 

 was mistaken in supposing that a type had been properly indicated, 

 so that it was not until 1909 that Venus pinguis was definitely 

 selected as its typical species, and that Samarangia was excluded 

 from the genus. The following is an abstract of the generic definition 

 then given by me : — 



Shell oval or oblong, inequilateral and oblique, smooth or con- 

 centrically striated. Lunule well defined, but escutcheon only 

 defined by absence of sculpture. Valve-margins smooth. Hinge- 

 plate short, witli three fairly strong, divergent, and nearly equidistant 

 teeth ; the right posterior and median, as well as the left median, are 

 bifid or grooved, and frequently all the teeth are rugose. The right 

 nymph and the left posterior tooth are striated with linear riblets; 

 the posterior right and anterior left dorsal margins are grooved. 

 Pallial sinus of moderate depth and rounded. Pedal scar separate 

 from that of the adductor. 



JIarcia, s.s. Type, Venus pinquis, Chem. 



Shell oval or oblong, convex, smooth or obscurely waved, often 

 attenuated posteriorly. Lunule distinct and impressed. Teetb rather 

 small and widely divergent, the left posterior rugose and confluent 

 with the nymph, left anterior and median both grooved. 



This group includes V. nehulosa, Glmm., paiipercula, Chem. (with 

 the varieties koclti., Pliil., amhigua, Desh., and hraiissi, Desh.), 

 ? internq)ta, Koch., and fiimigata, Sow. (= Icevigata, Sow.). It 

 inhabits the Indian Ocean from the east coast of Africa to Australia 

 and the Philippine Islands. 



Sub-genera. 



Hemitapes, Komer, 1864. Type, Vetius rimularis, Lam. 



Shell oval or sub-trigonal, convex, and generally tumid. Sculpture 

 of narrow irregular concentric ribs. Teeth short, the left posterior 

 obli(pie and only in part adherent to the nymph ; both the anterior 

 teeth are tall and entire. Pallial sinus fairly deep. 



This group is also East Indian and Australian, m(Au(\\\i^j:flammiculata, 

 Lam., striata, Chem., cor, Sow. {noti Hanley), philippii, Desh., 

 marmorata, Lam., variabilis, Phil, (with its varieties laterisulca, 

 Sow., orientalis, Desh., ustulata, Desh., and recens, Sow.), flammea, 

 Gmelin (= radiata, Chem.), and recens, Chem. (not Sow.). 



Katelysia, Romer, 1857. Type, Venus scalarina, Lamarck. 



Sliell obliquely oval, compressed or convex, anterior side very 

 short; sculpture of strong concentric ridges which are sometimes 

 corrugated by radial ribs. Teeth nearly straight, but divergent, and 

 all more or less rugose. Pallial sinus small, obtuse, or rounded. 



This is a small group of Australian shells comprising Vetius strigosa, 

 Lam., V. corrugata, Lam., V. peronii, Lara., V. aphrodina, Lam., and 

 V. regularis, Desh. To these may, I think, be added the shell 

 described by Deshayes as Saxidomus decussatus and said to come from 

 South America, but of which I have specimens from Japan. 



