Cerithiopsis.] 



GASTROPODA. 



245 



Shell small, thin, cylindro-conic, narrow ; protoconch polygyrate, 

 with a slightly deviated nucleus ; whorls numerous, tuberculate, 

 not varicose, the last narrower in proportion ; aperture small, sub- 

 quadrangular, with a short, truncate, nearly straight canal ; outer 

 lip thin, not produced at the base ; columella smooth, straight, not 

 twisted below, but simply inflexed towards the basal notch. 



Distribution. Mostly occurring in northern and temperate seas. 



Fossil. Cretaceous. 



KEY TO SPECIES. 



A. Shell with 2 cinguli on the spire-whorls. 



a. Axial riblet.s about 12. points of intersection with nodules. 



which are also present on the protoconch . . crenistria. 



aa. Axial riblets about 20, points of intersection with 



gemmules. protoconch smooth . . . . . . marginata. 



B. Shell with 3 cingiili on the spire-whorls. 



a. Canal notched at base. 



b. All cinguli with gemmules. 



c. Protoconch of 1^ whorls . . . . . . cessicus. 



cc. Protoconch of 3| whorls . . . . . . sarissa. 



bb Upper cinguli without gemmules, protoconch of 



li smooth whorls .. .. .. .. styliformis. 



aa. Canal not notched at base. 



b. Suture canaliculate . . . . . . . . canaliculata. 



bb. Sutxire not canaliculate, but deep. 



c. Suture margined, shell acicular . . . . acies. 



cc. Suture not margined, shell subulate . . subantarctica. 



1. Cerithiopsis acies, Suter, 1908. Plate 14, fig. 16. 

 Cerithiopsis acies, Suter, P. Mai. S., viii, 35, pi. 3, f. 40. 



Shell very small, acicular, rather solid. Sculpture consisting of 3 

 equidistant cinguli, the uppermost very thin and close to the suture, 

 which is margined above by a fine thread ; the last whorl with a fourth 

 spiral ridge emerging from the suture ; the spiral sculpture crossed 

 by slightly oblique axial riblets, also equidistant and of the same width 

 as the interstices, about 15 on the last whorl ; the points of inter- 

 section raised into round gemmules ; the axial sculpture is less pro- 

 minent than the spiral. Colour white. Spire high and narrowly 

 conical, much higher than the aperture ; outlines almost straight. 

 Protoconch polygyrate, cylindro-conical, of 4 slowly increasing, strongly 

 convex, and smooth whorls. Whorls about 10, convex ; base slightly 

 concave. Suture deeply impressed. Aperture subquadrangular, ver- 

 tical, with a short and widely open canal. Outer lip sinuated by 

 spiral sculpture. Columella vertical, slightly sinuate, pointed at the 

 base. Operculum unknown. 



Diameter, 1-1 mm. ; height. 3-5 mm. 



Animal unknown. 



Type in my collection. 



Hob. Port Pegasus, Stewart Island, in 18 fathoms (Captain 

 Bollons). 



