340 UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES. 



produced below; suture distinct, but not very deep; surface ornamented by 

 numerous small, slightly-arched, vertical costse, crossed by much smaller, 

 thread-like, revolving lines; aperture rather broad-ovate, being angular above, 

 most convex on the outer side, and subangular, or narrowly rounded, and 

 slightly effuse at the inner side of its base ; inner lip thin or nearly obsolete. 



Length, about 1.65 inches; breadth, 0.68 inch ; length of aperture, 0.55 

 inch ; breadth of same, 0.37 inch. Slopes of spire very nearly straight, with 

 a divergence of 28°. 



The little vertical costse on this shell number about twenty-two to 

 twenty-three on each turn, and are usually separated by depressions some 

 three or four times their own breadth. They are rather angular, but not 

 very prominent. About thirteen of the small revolving lines may be counted 

 on the second turn, where they are separated by spaces nearly twice their own 

 breadth. On the last whorl, a smaller line, and sometimes two or three 

 smaller ones, are developed between each two of the larger revolving lines, 

 so as to give the whole a more crowded and irregular appearance. 



Among foreign fossil forms, this species may be compared with Scalaria 

 gurgitis of Pictet and Roux (Mem. Soc. Phys. et Nat. Hist, de Geneve, XII, 

 pi. 16, fig. 4), which it nearly resembles; though it differs in having a less 

 attenuated form aid a smaller number of volutions than the European 

 species, which is probably not a true Scalaria. 



I have long been in doubt in regard to the generic relations of this shell. 

 Originally, we supposed that it belonged to some section of the genus Sca- 

 laria, to which genus we at first referred it; and this opinion was, of course, 

 also held at the time we placed it under the equivalent name Scala. Better 

 specimens, however, show that it differs from that genus in not having its 

 peritreme continuous, and in having its aperture more angular behind, as well 

 as subangular and slightly effuse at its inner side below. Its volutions are 

 likewise less convex, and do not round into the suture above, as we see in 

 that genus. From all of its known characters, it seems to be very much 

 more nearly allied to Ghemnitzia as that genus is here defined. Indeed, we 

 at one time held the opinion, long back, that it belonged to that genus, as 

 understood by many who consider it a synonym of Turbonilla, Risso. 



The name cerithiformis having been previously used in the genus 

 Scalaria, to which we at first referred this species provisionally, Professor 

 Nvst proposed to call it S. Mcehi ; but, as we now know that it is not a 



