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PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



posterior pit, and with the edge raised into four cusps ; the posterior 

 tooth heing oblique, narrow, elongate, curved, with the edge raised 

 into two slight points. With the actual valve before me, it is possible 

 to understand this description, except that I can find only three cusps 

 upon the so-called anterior tooth. 



By comparing the figure of C. isocardia 1 (Fig. I) with those of 

 various species of Caryatis given by Bonier, 2 the similarity in the 

 binge is fairly observable, and an examination of the several species, 

 side by side, shows that there is no essential difference between any 

 of these forms. The two diverging teeth beneath the umbo in the 

 left valve of C. isocardia do not, however, form such an acute angle as 

 usual in the section Caryatis, and the pit between them is peculiarly 

 deep. The teeth of the right valve, although thin and delicate, agree 

 exactly in form and position with those of other species of the genus. 

 Owing to the tenuity of the valves, the muscular scars are very 

 indistinct, and the pallial line is scarcely traceable. It is therefore 

 impossible to say, from the specimens examined, to what extent it 

 may be sinuated. 



Fig. II. — Vesicomya lepta. 



The hinge of Vesicomya (Fig. II) is lighter and less complicated than 

 that of Caryatis, and the different species exhibit slight modifications 

 which could only be understood from enlarged and accurate 

 drawings. The pallial line in this genus is scarcely sinuated 

 in some species, whereas in others it is somewhat deeply inflected. 

 The following species, which are quoted under their original names, 

 probably belong to Vesicomya : — 



1. Callocaedia (?) Atlantica, Smith: Beport Challenger Exped. 

 Lamellibr. (1885), p. 157, pi. vi, figs. 8-8/;. 



Sab. — West of Azores, in 1,000 fathoms. 



2. Callocaedia (?) Pacifica, Smith: op. cit., p. 156, pi. vi, 

 figs. 9-93. 



Hal.— Mid North Pacific, in 2,900 fathoms. 



3. Callocaedia (?) Adamsii, Smith: op. cit., p. 155, pi. vi, 

 figs. 7-75. 



Hob.— South of Sierra Leone, in 2,450 fathoms. 



1 Proc. U.S. Nat. Mus., vol. xii (1899), pi. x, fig. 5. 

 3 Novit. Couch. Venus, Ed. i, pis. xxii-xxxiii. 



