RissoA. 297 



Rissoella? eburnea. 



Rissoa eburnea, StimpsOxV, Proc. Bost. Soc. iv. 14 (1851) ; Shells of New England, 34, pi. 



l,fig. 1. 

 Rissoella ? eburnea, Stimpsom, Check Lists, 4. 



Shell small, ovate-conoid, white, shining, smooth ; whorls Fig. 564. 

 four, rather convex, sub-angulated at suture ; aperture ovate- 

 elliptic ; peristome thin, simple, acute, effuse anteriorly. 

 Length, sixteen hundredths of an inch ; breadth, nine hun- 

 dredths of an inch. 



This species resembles some varieties of R. ventrosa, but 

 is much more angular. Two specimens were taken in thirty 

 fathoms, off Cape Ann (^Slimpsoii'). 



Rissoella sulcosa. 



Shell minute, ovate-conic, smooth ; whorls four, sub-convex, transversely fur- 

 rowed ; suture impressed ; aperture ovate-oblong, transversely banded within. 



Phasianella sulcosa, Mighels, Bost. Journ. iv. 348, pi. 16, fig. 4 (1843). 

 Rissoella ? sulcosa, Stimpson, Check Lists, 4. 



Shell very small, ovate-conical, smooth and white ; whorls four, 

 slightly convex, with six or seven transverse grooves on 

 the body whorl, and three on each of the two next above, ^'"' 

 spire smooth and pointed ; aperture ovate-oblong, with 

 three slightly apparent transverse bands within, as seen 1 

 under a strong magnifying power. Length, one tenth 

 of an inch ; breadth, about one twentieth of an inch. „ , 



' ' R. sulcosa, 



Casco Bav. 



Examined with the unassisted eye, this shell would be likely to 

 be mistaken for some species of Citm-ida, but its true character is 

 revealed with even a moderate magnifying power, the lip being in- 

 conlinuous posteriorly. I have never discovered but one specimen 

 of this curious little shell ; this I found in the stomach of a had- 

 dock, in the summer of 1842. I presume it is the only representa- 

 tive of the genus that has been hitherto discovered on our Atlantic 

 coast (^Mighels'). 



Oenus RISSOA, Fremenville. 1814. 

 Shell usually white, solid, conical; spire pointed, many wliorled, 

 whorls convex and smooth, or longitudinally ribbed ; aperture ovate ; 

 outer lip more or less dilated and thickened externally. 



