OF CONCHOLOGY. 257 



inore central, blunt and erect; the shell is less convex, polished 

 and delicato, though smaller than virginea ; and if the two were 

 found in the same locality they would both be recognized by 

 most conchologists as distinct species. A shell which is more 

 nearly allied to, though very distinct from, rosacea, is Patella 

 puncturaia, (Lam.) Rve., Icon. No. 122, from Honduras and 

 Aspinwall. Still closer is Acmcea {Collisella?) a'qualis, Cpr. 

 MSS. from the Gulf, yet it seems to be distinct, from the single 

 dearl specimen known to me. 



I have doubts as to the genus of this species, which may be a 

 patellid. 



" Acnura pileolus," Midd., I believe to be a variety of pelta, 

 as Dr. Carpenter suggests ; at all events the figure and diag- 

 nosis do not give any characters common to this or any other of 

 the southern species. Dr. Carpenter says that the types (in 

 Mus. Cuming) of Middendorf's species are rosacea, yet I believe 

 with him, that some mistake has certainly occurred ; as rosacea 

 is not to be found at Sitka, the locality of pileolus, and the de- 

 scription and fi;gures cannot be reconciled. 



This name of Middendorf's had better be dropped entirely, 

 as it is impossible to determine, Avith certainty, what his shell 

 was, and its retention can only create confusion. 



Collisella araucana, D'Orb. 



Patella araucana, D'Orb., Voy. Am. Mer. v, p. 482, No. 448, 

 ix, pi. Ixv, fig. 4 — (5. 



The animal of this variable species is brownish, and agrees in 

 every essential particular with the other known species of this 

 section. The uncinus is short and somewhat notched or bifid at 

 the extremity. The specimen examined came from the Chilian 

 coast near Valparaiso. 



Collisella (?) sybaritica, n. sp. Plate 17, fig. 34. 



Shell depressed, thin ; apex subcentral, more anterior in the 

 young. General shape rounded oval, hardly more narrow before 

 than behind. Surface nearly smooth, with rounded concentric 

 lines of growth ; in young specimens a few faint, hardly notice- 

 able elevated radiating lines or riblets may be observed near the 

 margin, which is entire. Internally smooth, border polished and 

 also the cavity of the apex above the muscular impressions. 

 Color a clear rose pink, varying from quite deep and a little livid 

 in some specimens, especially the young, to a very faint pink. 

 Apex white, even in very young specimens entirely uneroded, 

 rather blunt and inconspicuous ; sides of the shell ornamented with 

 rays of a darker shade of pink, more or less gathered in groups, and 



