248 BULLETIN OF THE 
The var. obliterata is as a rule mcre 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 N. Verrillii 
(N. trigona 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 Jeffreys is more globose, smaller, and more delicately 
sculptured. 
Famity LEDIDAL, 
Genus LEDA Scuoumacuer. 
Suscenus YOLDIA Morcu. 
Yoldia solenoides Dat. 
Yoldia solenoides Dall, Bull. M. C. Z., IX. p. 127, 1881. 
Plate IX. Figs. 2, 2a. 
Habitat. Station 49,118 fms. Lat. 28° 51’.5 and W. Lon. 89° 1/.5, in the 
Gulf of Mexico, no temperature noted. 
No additional specimens have turned up, 
Yoldia liorhina Datt. 
Yoldia liorhina Dall, Bull. M. C. Z., IX. p. 127, 1881. 
Plate IX. Figs. 1, la. 
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. 
