74 



THREE CRUISES OF THE " BLAKE. 3 



largest known species being one of the " Blake " treasures, V. 



elegantissima Dall (Fig. 308), a 

 brilliant pearly shell ; one of the 

 smallest is V. perversa Dall (Fig. 

 309), which has the larger bulge 

 in front of the hinge, contrary to 

 the usual rule. 

 A lovely new group related to Thracia and Anatina is repre- 



Fig. 307. Cuspidaria microrhina. j. 



Fig. 308. Verticordia ele- 

 gantissima. ^. 



Fig. 309. 

 Verticordia 

 perversa. 



Fig. 310. Bushia ele- 

 f 



sented in deep water by a single species, which has been named 

 Bushia elegans. (Fig. 310.) 



We may also mention, as evidently a deep-water group, the 



shells of the subgenus Meiocardia, re- 

 lated to Isocardia cor of Europe. 

 These are remarkable for the way in 

 which the tips of the valves are 

 twisted and turned away from each 

 other, 

 fossils ; 

 species 



Isocardia cor, these are tropical. 

 The dredgings of the " Blake " and the " Albatross " have re- 

 vealed a new Meiocardia in the Antilles, the others being all 

 Oriental, and this has been named M. Agassizii. (Fig. 311.) 



A new group, differing from Isocardia and Meiocardia in hav- 

 ing no lateral teeth, is Vesicomya, previously unknown from 

 American waters, the largest known species of which is a form 

 now named V. venusta (Fig. 312), from Antillean specimens. 

 A much smaller species, named V. pilula, is reported by the 



Fig. 311. Meiocardia Agas- 

 sizii. 15. 



They are common tertiary 

 but only a few living 

 are known, and, excepting 



