CYLICHNA. 297 



In this species the apical whorl is smooth, upturned, and sunken 

 in a shallow pit formed by the two succeeding whorls, one rising a 

 little above the other, with a slightly rounded sutural margin. In 

 some specimens these are so closely coiled as nearly to conceal the 

 nucleus, while in others each turn is visible. The following turns 

 are more loosely coiled, and the outer lip joins the body whorl a 

 little below the apex of the shell. Some of the Fish Commission 

 specimens are considerably larger than Mr. Dall's types, and more 

 slender in proportion to their length. One i^erfect specimen is I62 

 mill, long and 8 broad ; another worn and broken one is about 29 

 mill, long and 13 broad ; while still another is 23 mill, long and 11 

 broad. (Bush.). 



A careful study of the radiila and gizzard shows that the correct 

 position of the species is with the Cylichnse. The radula consists of 

 a series of strongly hooked, dark amber teeth, the lateral ones with 

 broad curved bases and the marginal ones with simple straight 

 bases, arranged in rows of five or seven on each side of the minute 

 median tooth, in small specimens these hooks are distinctly rough- 

 ened on the under surface by fine, raised longitudinal lines. The 

 three plates of the gizzard are club shajjed, with a yellow-white 

 flattened exterior surfiice and a dark reddish-brown convex interior 

 surface, the greatest convexity situated beyond the middle, in the 

 broader end, with a little flattened space in front defined by a lighter 

 shade of color. {Btish). 



a DALLi Verrill. PI. 48, fig. 13. 



Shell elongated, white, translucent, somewhat barrel-shaped, a little 

 broader medially, but nearer the anterior end ; considerably nar- 

 rowed posteriorly, with a small pit at the apex. No umbilicus. 

 Aperture as long as the shell, very much narrowed posteriorly, and 

 ending in a narrow slit in the sutural line ; anteriorly it increases 

 gradually about to the anterior third, when it suddenly expands into 

 an ovate anterior portion, by the strong excurvature of the col- 

 umella margin, and a slight expansion of the outer lip. The outer 

 lip rises, posteriorly, slightly above the level of the body-whorl, in 

 the form of a thin edge, separated from the body-whorl by a narrow, 

 deep fissure ; passing backward it forms a gently sloping shoulder, 

 and is very slightly convex and divergent to the anterior end, where 

 it is cut away for the entire width of the shell, and joins the col- 

 umella lip in a regular curve, with a sharp edge, not reflexed ; the 

 columella-raargin is strongly excavated and sinuous and in the 



