RISSOA. 87 



suture, and end in an obtuse apex. These turns are well 

 rounded, yet shelving : their longitudinal increase is rather 

 quick, especially that of the penult, which is somewhat large 

 in proportion to the rest, its length being nearly its breadth. 

 The body is well rounded, and not produced ; its basal 

 declination is convex, and moderate. The aperture is sub- 

 orbicular or rounded-ovate, occupies about two-fifths or 

 rather more of the total length, and is not distinguished by 

 any peculiar sculpture. The throat is smooth ; the lips con- 

 tinuous, and both of them considerably and nearly equally 

 arched. The outer one is thickened behind, and although 

 not patulous, juts out very distinctly (instead of receding, 

 as in certain shells) at the anterior extremity ; the inner 

 one is narrow, and is not followed by any umbilical chink. 

 The pillar is much curved. The average length of ex- 

 amples is only the tenth of an inch, with an extreme 

 breadth of scarcely three-quarters of a line. 



Although one of the rarest and most recently discovered 

 of our Bisso^, we have been so fortunate as to meet with 

 and examine the animal. It has a short and rather narrow 

 muzzle ; the tentacles are long and linear ; the eyes large 

 for the size of the creature, black, and placed on rather 

 more prominent bulgiugs than usual. The foot is capable 

 of great elongation in front, where it is angulated and mar- 

 ginated, behind it is pointed ; immediately behind the 

 operculum is a single, rather short, but conspicuous cirrhus. 

 The entire animal, except the eyes, is of a milky white. 



It was first dredged alive in one hundred fathoms, on a 

 muddy bottom in Loch Fyne (M'Andrew and E. F.); JSIr. 

 Jeffreys and Mr. Barlee have taken it off Oroulin Island 

 on the coast of Skye. Mr. M'Andrew has also dredged 

 it in sixty fathoms, fifteen miles to the S. W. of Mizen 

 Head. It is probably a member of our boreal fauna. 



