74 THREE CRUISES OF THE " BLAKE." 



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



elegantissima Ball (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. -I. 



Fig. 308. Verticordia ele- 

 gantissima. I. 



Fig. 309. 

 Verticordia 

 perversa. 2, 



Fig. 310. Bushia ele- 



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. They are common tertiary 

 fossils; but only a few living 

 species are known, and, excepting 

 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 



f o 



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. Ji6. 



