242 AMERICAN JOURNAL 



the right ; on the left side is a border formed by an impressed 

 line which extends from the base to the apex of the organ ; a 

 large vessel sends forth branches to the lamellae from this side. 

 The laminje are very prominent, so that the gill appears very 

 thick and stout. Clo3e to the adductor on the extreme right are 

 (1) the anal tubercle, small, conical, pointing to the right, and (2) 

 the infra-anal* papilla, smaller than the other and to the right 

 of it. The renal orifice is probably very minute and situated to 

 the left of the anal tubercle, but a thorough search failed to de- 

 tect it. Intestine regularly and repeatedly constricted toward 

 its termination, expelling the faeces in cylindrical pellets. In 

 all the specimens examined it was full of white calcareous re- 

 mains of nullipore. 



Shell dull white, aperture nearly circular, wider behind, in 

 some young examples somewhat elongated oval ; form conical, 

 apex erect, nearly central, blunt, smooth ; posterior surface 

 usually straight but occasionally a little convex, exterior smooth, 

 marked with very faint concentric lines of growth ; devoid of 

 epidermis ; margin entire, polished, with a narrow serai-pellucid 

 rim inside. Internally smooth or furnished with grooves radia- 

 ting from the apex more or less strongly marked. Muscular im- 

 pressions deep, strong, horseshoe-shaped, with the marks of the 

 anterior ends of the adductors rounded and broader than the 

 rest, connected by a slender impressed line marking the attach- 

 ment of the mantle. Young shells are often furnished with ir- 

 regular riblets more or less strong, many or few in number, 

 radiating from the apex but stronger towards the margin. Color, 

 dead white inside and out, often livid, or tinged a fine pink or 

 pea green from nullipore, but never wax yellow or horny pellu- 

 cid as in the normal state of Scurria scurra. Formula 



_0 



0(1^IT:-1.1— 1—1)0. 



I have been thus explicit because, by almost every author ex- 

 cept Dr. Carpenter, this shell has been confounded with the South 

 American species above mentioned ; which, however, belongs to a 

 different genus. Taken together, the most conservative concholo- 

 gist would hardly think of uniting them ; short descriptions and 

 poor figures are mostly to blame for the confusion. The striated 

 variety [tenuisculpta, Cpr.,) appears very distinct from the smooth 

 form, but every gradation may be found in a very large series. 

 The unique type of Scurria? funieulata, Cpr., now before me, dif- 

 fers from the smallest specimen of tenuisculpta, only in having the 

 riblets even more prominent, close, and rounded, and being 



* Infra-anal orifice of Lankester; see remarks under Patella vulgata. 



