OP OONCHOLOGY. 315 



of an inch long, it begins to throw off a light drab portion 

 posteriorly, the black projecting into it in broad rays; the 

 shell, at the same time, developing coarse, faint ribs. A spe- 

 cimen, about -2 inch long, which was adhering to an adult, 

 and is probably conspecific, is entirely drab, of rough, irregu- 

 lar growth, and with but few broAvn spots. A series is want- 

 ing to connect these very young shells with the adolescent 

 specimens. 



Some of the Chilian limpets, which have been bandied 

 about between Patella and Acmsea, may possibly prove to be- 

 long to Lottia as now restricted. 



Genus SCUEEIA, Gray. 



Dr. Alcock writes, that "in Scurria mitra the mantle-margin 

 is beset within with lamellar papilliB. extending completely 

 round, but less developed in front; the foot is thick and round- 

 ish oval; the gill moderate, triangular, and broad at the base. 

 In the typical Acmiese, {patina^ j)elta^ fascicularis) the mantle- 

 margin is plain within; the foot oval; the gill long and plume- 

 like. In A. discors, however, the gill is triangular, with a 

 broadish base, as in Scurria.''' It appears evident that the 

 anatomical details have not yet been examined in a sufficient 

 number of species to ascertain what characters are generically 

 important, and what of specific value only. All grouping 

 according to the shells alone, is manifestly erroneous. The 

 absence of true Patellse from the whole Northern coasts of 

 America is very remarkable. 



SCUERIA MITRA, Escholtz. 



= Acmsea m.-^A.mamillata-\-A.marmorea, Eschscholtz, Zool. 



Atlas, PL 5, pp. 18, 19, p/. 23,/. 4. 

 = f Lottia pallida, Gray, Zool. Beech. Voy. 

 = Patella conica, Gould, PJxpl. Exped. Moll, p.S4:6, {Jrom type) 



This shell, which is profusely abundant and large in the 

 Vancouver district, varies considerably in outline, but is al- 

 ways very conical, with the apex elevated and pointed, even 

 in very young specimens. As generally seen, the surface is 

 smooth, even in fresh shells, and after the nullipore has been 

 uncoated; but occasional specimens present faint indications 

 of striae, as stated by Dr. Gould. Whether this be co-ordinate 

 with any differences in the animal, has not been ascertained. 

 Fresh Southern specimens are sometimes found (as from Mon- 

 terey, Cooper) with a delicate pink tinge; but the dead shell 

 is uniformly of a pure white, not yellowish or ashy like the 

 South American Scurria scurra, Lesson. Dr. Gray (and Dr. 



