MOLLUSCA. 835 



cave; the outer and lower surfaces of the volutions rounded; 

 outer surface marked by two rows of nodes nearly equal in 

 prominence, one of them situated near the middle of the height, 

 the other near the lower margin ; surface of the volutions marked 

 by oblique, transverse folds or ridges which increase in number 

 by division or intercalation at the upper and lower margins of 

 the outer surface; the ridges are strongly directed forward as 

 they cross the volution from the upper tO' the lower side, and are 

 even faintly visible within the umbilicus; the nodes in each row 

 are usually present upon alternate ribs, the ribs of the two rows 

 alternating with each other so' that nearly every rib has one node 

 in either the upper or the lower row. The suture with a ventral 

 lobe lying between the higher row of tubercles and the upper 

 margin of the outer surface of the shell; it is indented in the 

 middle by a rather broad siphonal saddle ; below the ventral lobe 

 the first lateral lobe is very large with four larger divisions; it 

 is. nearly bisected by the lower row of tubercles which mark the 

 lower shoulder of the volutions ; a second lateral lobe much shal- 

 lower than the first, but rather broad, is present upon the lower 

 side of the volution just outside the umbilical cavity; the two 

 lower lateral saddles are both broad, the first one being some- 

 what larger than the second; both are rather deeply bifid with 

 each of the divisions again bifid ; above the ventral lobe the lateral 

 lobes and saddles are similar to those below but are smaller; all 

 the lobes and saddles are secondarily indented by tooth-like 

 irregularities. 



The dimensions oi the type specimen are: diameter of last 

 volution, 29 mm.; height of last volution near the aperture, 16.5 

 mm.; width of last volution near aperture, 13 mm. 



Remarks. — ^The type specimen of this species retains about one 

 and one-third volutions, the greater portion of which is occu- 

 pied by the living chamber, only the first suture and a portion of 

 the second being retained. Two other specimens have been ob- 

 served which are referred to the species with some doubt, both 

 of them are mwch distorted fragments which differ in some re- 

 spects from the type but are too imperfect for certain identifi- 

 cation. 



