20 PALAEONTOLOGY OF CALIFORNIA. 



on the sides; separated from each other by about one-third the 

 width of the volution. Surface marked by fine lines, which arise 

 in the umbilicus ; curve slightly backwards and then forwards on 

 the side, and, as they pass over the angle between the side and 

 back, again curve backwards, making a deep sinus on the dor- 

 sum. 



This shell is allied in form to N. bidorsatus, ScWot. The sides are, in the pre- 

 sent species, more strongly inclined towards each other; and the dorsum is con- 

 vex, instead of being excavated. The umbilicus also is smaller. 



Locality : With the preceding species. 



N. MULTICAMERATUS, U. S. 

 PL 3, Figs. 4, 5. 



Shell broad, subglobose; whorls deeply embracing; sides com- 

 pressed and rapidly converging ; dorsum broadly grooved ; um- 

 bilicus apparently quite small, partially obliterated in the speci- 

 men. Septa numerous, crowded, arching forwards on the sides, 

 and curving slightly backwards on the back. Siphuncle unusually 

 large. Surface marked by revolving, somewhat irregular elevated 

 lines. 



Figure, natural size. 



Locality: A single specimen was found by Mr. R. Homfray at "Dun Glen," 

 near the Auld Lang Syne Mine, Sierra District, Humboldt County, Nevada Ter- 

 ritory. 



