OF CONCHOLOGY. 249 



Var. ochracea, Dall. Plate 17, fig. 35. 



There is another very well marked and pretty variety which 

 1 should refer to this species, and as it does not appear to have 

 been described, I would propose for it the name of ochracea; 

 externally it is of a very light yellowish brown, without spots or 

 rays ; internally white with the characteristic dark brown st;un 

 of patina in the visceral area. The exterior is covered with fine, 

 regularly radiating, close, equal, thread-like riblets, which pass 

 from apex to margin without bifurcation, imbrication or asperities 

 of any kind. These riblets will serve to distinguish it from any 

 of the other limpets of the coast ; otherwise it approaches very 

 close to some varieties of scabra, and can be traced right into 

 varieties of patina. The variation of these limpets appears to 

 be absolutely without limits ; you may describe seven hundred 

 forms as easily as seven. The only guide to specific identity is 

 a certain habit of growth, easier seen than described, and very 

 easy to overlook. 



The home of the normal form may be said to be the Van- 

 couver district, whence it extends northward to Cape Spencer, 

 and southward to Saa Diego. The centre of radiation of the 

 variety Oiimingii is about Kadiak, whence it extends west and 

 north to the Pribylof group in Bering Sea and the Aleutian chain, 

 and south to Vancouver, strat;2liiitr specimens even occurrinoj 

 about San Francisco. I have dredijed it at six fathoms in Unii-a, 

 North harbor, but they are usually found about tide marks. 



COLLISELLA TESTUDINALIS, Mull. Sp. Date 14, fig. 13. 



Patella testudinalis, Mull., Prodr. Zdol. Dan. p. 237, 1766. 



Mantle with very fine papilloe around the edge which is col- 

 ored in accordance with the margin of the shell, variable in dif- 

 ferent individuals. Tentacles long, slender, sharply pointed ; 

 eyes small on the upper posterior bases of the tentacles, which 

 are rather swollen, with a strong tubercle on the inner side of 

 each tentacle. Head large, rounded ; muzzle short, with a wide 

 thin puckered frill, not prorluced into lappets as in Aenicea ; 

 central disk granulose, mouth subcircular. Gill free all its 

 length, situated in the commissure, between the mantle and neck 

 on the left side, slender, elongate-triangular, pointing toward 

 the right over the head, extensile beyond the edge of the mantle, 

 whitish. Anal papilla obliquely truncate, situated close to the 

 adductor on the right side, orifice internally papillose ; infra, 

 anal tubercle close, to the right of anal, minute, somewhat elon_ 

 gated. Renal orifice not detected, probably extremely minute 

 and to the left of the anal tubercle. Formula , ,,,/',_,.,,., . 



