MOLLUSCA. 721 



Genus RosTEttARiA Lamark. 



Rosteliaria curta Whitfield. 



Plate LXXXIIL, Figs. g-13. 



1892. Rosteliaria cv/rta Whitf., Pal. N. J., vol. 2 (Monog. U. 

 S. G. S., vol. 18), p. 109, pi. 13, figs. 9-13. 



Description. — "Shell small and comparatively short for a 

 species of the genus; spire short, the apical angle being about 45° 

 in some specimens, and in other individuals rather less ; volutions 

 convex, four or five in number, only four in the casts; sutures 

 deeply marked, indicating a comparatively thick shell ; body volu- 

 tion large, half as long as the entire length of the cast, or some- 

 times three-fifths of the entire length ; base of the body volution 

 extended in front; aperture equaling one-half the length of the 

 cast; elongate elliptical in outline, acute at the upper angle and 

 the margin extending abqve the line of the suture where the 

 lip has extended upon the preceding volution; lower margin of 

 the aperture prolonged and narrow; outer margin more con- 

 vex than the inner; columellar cavity rather large, indicating a 

 strong and thickened columella, which has been smooth and with- 

 out any indications of folds or markings ; surface of the volutions 

 marked by distant but not very strong vertical folds, which are 

 only seen on the internal cast upon careful examination; surface 

 of the shell and features of the lip and posterior canal unknown." 

 (Whitfield.) 



Remarks. — The broad columellar cavity in the casts of this 

 species gives it a strong resemblance tO' the casts which have 

 been referred tO' the genus Turbinopsis by Whitfield, and so far 

 as the characters of the casts are concerned there seems to be nO' 

 reason for placing this species in a different genus than Turbi- 

 nopsis elevata. Indeed, in many respects these two species seem 

 to be closely allied, but R. curta is smaller, with a shorter and 

 more pointed spire. Whitfield's illustration showing the revolv- 

 ing costje near the aperture (his fig. 10), is much overdrawn, 



46 PAL 



