RISSOA. 



297 



Rissoella? eburnea. 



Rissoa clmrnca, Stimpson, Proc. Bost. Soc. iv. U (1851) ; Shells of New England, 34, pi. 



1,%. 1. 

 Rissoella 1 eburnea, Stimpson, 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. vcntrosa, but 

 is much more angular. Two specimens were taken in thirty 

 fathoms, off Cape Ann {Stiinpsoii). 



Rissoella sulcosa. 



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

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



Phasianclla sulcosa, Mighels, Bost. Journ. iv. 348, pi. IG, tig. 4 (1843). 

 Rissoella? sulcosa, Stijipsox, 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 ^ 

 under a strong magnifying power. Length, one tenth 

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



Casco Bay. 



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

 be mistaken for some species of Cingtila, but its true character is 

 revealed with even a, moderate magnifying ])Ower, the lip being in- 

 conliiiHous 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). 



Ocnus RISSOA, Fremenville. 1814. 

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

 whorls convex and smooth, or longitudinally ribbed; a})erture ovate; 

 outer lip more or less dilated and thickened externally. 



