Shell small, thin but strong and solid, elevated, conical, the base short-oval, apex erect, a little in front of the middle; slopes of the cone somewhat convex. Surface lusterless, usually corroded, smooth except for very fine radiating striae visible with the aid of a lens, but obsolete in adult shells. Color rusty black. Inside black, with a brown zone just outside the musclescar. Length 10, breadth 8,2, alt. 7 mm.

Shell. High profile; apex in anterior third of shell. All slopes straight to slightly convex. Sculpture of radial riblets usually visible only at the margins. Gray-black to black. Interior black. Length, 5-10 mm. Animal. Lacks pigmentation.

Radula (See picture). First lateral teeth closely set on anterior edge of ribbon segment, rounded distally. Second lateral teeth posterior to first lateral teeth; broad, rounded distally. Third lateral teeth lateral to second lateral teeth; wedge-shaped, reduced. Uncini large. First lateral plates rectangular; posterior edge of second lateral plates straight, second lateral plates separated from third lateral plates by small partial suture; posterior edge of third lateral plates with slight indentation. Ventral plates subrectangular with rounded posterior process.

In the suite of thirty or more of this species before me, no specimens show characters which warrant a union with any of the other species. It is an erectly conical, solid little shell, of a more rounded outline than A. insessa, and black instead of corneous in color. It is generally found living on Chlorostoma funebrale or other black shells.

Packard (1918:300) erroneously cited Carpenter (1864a:650) when he reported the presence of this species in San Francisco Bay. Carpenter (loc. cit.) reported L. asmi from the Farallon Islands, located approximately 50 km west of San Francisco. Although typically found on Tegula funebralis, L. asmi has been reported from other substrates by numerous workers including: Keen and Doty (1942), Test (1945), Long (1968), and Eikenberry and Wickizer (1964). Several other species of limpets also occur on T. funebralis and may be confused with L. asmi, particularly L. pelta. The interior of the shells may be used to distinguish between these two species. Lottia pelta has a blue-white intermediate area while L. asmi has a black intermediate area. Lottia asmi is the only species of Lottia found along the California coast having the prominent posterior process on the ventral plates of the radula. See Brewer (1975) for a discussion of other epizooic limpets found on T. funebralis on the outer coast.

Northeast Pacifik. From Alaska to Turtle Bay, Lower California.
Sitka, Alaska (57°N) to Punta Pequena, Baja California, Mexico (26° 14TSf). Also Isla Socorro, Revillagigedo Islands, Mexico (19°N) (McLean, 1966:69.) San Francisco Bay: San Francisco County—St. Francis Yacht Club Breakwater, Black Point.