RISSOA. 105 



which varies considerably as to depth and purity: the, 

 throat is white and quite smooth. The outer lij), whose 

 acute edge is for the most part somewhat thickened at 

 the top, and is marginated externally by a solid white rib 

 or varix, that is never painted with a crescent-like linear 

 mark as in parva, is well arcuated, advances a little in the 

 middle, and is disposed to expand at the base. The 

 curvature of the inner lip is much less than that of the 

 opposite margin : the pillar-lip is shelving, not particularly 

 broad, and is slightly raised at the inner or attached edge, 

 but displays no umbilical crevice. Minute and crowded 

 longitudinal wrinkles are often perceptible upon the labial 

 varix. 



The length of a fair-sized example was the fifth of an 

 inch ; its breadth a single line. 



This is a southern form on our shores. It occurs in 

 Herm, dead on the shore ; at Ryde in company with 

 lahiosa ; at Torquay along with parwa (S. H.). Mr. Alder 

 who first recorded it as British, procured it from small 

 sea-weeds collected in Torbay, " where it appears to be 

 tolerably abundant." Exmouth (Clark) Weymouth ; 

 Manorbeer (Jefii-eys) ; Dawlish (Mrs. R. Smith) ; Brook, 

 in the Isle of Wight ; " Roundstone and Birterbuy bays 

 on the western coast of Ireland, where it was found by 

 Dr. Farran and Mr. Barlee (W. Thompson) ; Cork (Jef- 

 freys). 



It ranges to the Mediterranean ; Mr. M'Andrew has 

 taken it on the coast of Spain. 



VOL. 111. 



