248 BULLETIN OF THE 



The var. obliterata is as a rule more trigonal and more compressed than the 

 typical form. In some specimens the beaks are very prominent vertically. 

 Its faint sculpture will always enable it to be distinguished from jV. Verrillii 

 (^N. trigone Verrill, Trans. Conn. Acad., VI. p. 438, 1885, not of Bronn or 

 Seguenza, 1877), which has a smooth margin, while the smoothest obliterata 

 always show minute crenulations. Extreme specimens of the type and vari- 

 ety would be taken by any one as distinct species without the connecting 

 series. N. cancellata JeflFreys is more globose, smaller, and more delicately 

 sculptured. 



Family LEDID^ 



Genus LEDA Schumacher. 



subgends yoldia morch. 



Yoldia solenoides Dall. 



Yoldia solenoides Dall, Bull. M. C. Z., IX. p. 127, 1881. 



Plate IX. Fisrs. 2, 2 a. 



Habitat. Station 49, 118 fms. Lat. 28° 61'.5 and W. Lon. 89° 1'.5, in the 

 Gulf of Mexico, no temperature noted. 

 No additional specimens have turned up. 



Yoldia liorhina Dall. 

 Yoldia liorhina Dall, Bull. M. C. Z., IX. p. 127, 1881. 

 Plate IX. Figs. 1,1a. 



Habitat. Sigsbee, off Havana, 182 fms. ; Station 23, 190 fms,; Station 33, 

 1568 fms. 



The cartilage is large and black, and inserted on a wide triangular space 

 directly below the beaks, but in the dead valve from Station 33 the place of 

 the cartilage is very small, though the shell is otherwise identical with the 

 others. The only living specimen, from 182 fms., shows no external liga- 

 ment, but the dead valve referred to might almost be taken for a Solenella or 

 Malletia. 



