102 American Seashells 



Subgenus Collisella Dall 1871 

 Pacific Coast Species 



Acmaea pelta Eschscholtz Shield Limpet 



Plate i8n 



Alaska to Lower California. 



I to I % inches in maximum diameter, elliptical in outline, with a mod- 

 erately high apex which is placed Vs to almost % way back from the anterior 

 end. With about 25 axial, weakly developed, radial ribs. Edge of shell slightly 

 wavy. External color of strong black radial, often intertwining, stripes on a 

 whitish cream background. Interior usually faint bluish white, with or with- 

 out a dark-brown spot. Inner border edged with alternating black and cream 

 bars. A common rock-dweller. 



Acmaea fenestrata Reeve Fenestrate Limpet 



Plate i8t 



Alaska to Lower California. 



I to I /4 inches in maximum diameter, almost round in outline, rather 

 high, and smoothish. The northern subspecies, cribraria Gould (pi. i8w), 

 found from Alaska to northern California, has interior with various shades of 

 glossy, chocolate-brown, and with a narrow, solid black border. The exterior 

 is plain dark-gray. The typical southern fenestrata Reeve (pi. i8t), found 

 from Point Conception south, has an external color pattern of regular dot- 

 tings of cream on a gray-green background. Its interior has a small, brown 

 apical spot surrounded by a bluish area and bordered at the margin of the 

 shell with brown. Intergrades occur near Point Conception. This species is 

 the only Pacific Acmaea which lives among loose boulders that are set in sand. 

 It only feeds when submerged. Common. 



Ac7naea conus Test Test's Limpet 



Plate i8g 



Point Conception, Cahfornia, to Lower California. 



% inch in maximum diameter. Shell low, and like A. scabra, is with 

 distinct but widely spaced, radial ribs. Distinguished from scabra by its 

 glossy, smooth interior which often has an evenly colored brown center. 

 A. scabra has a rough interior center and the brown stain looks smeared. 

 However, this species may be a form of scabra. It is very abundant south of 

 La Jolla and is found with A. scabra and A. digitalis. 



Acmaea limatula Carpenter File Limpet 



Plate 18-0 

 Puget Sound to Lower California. 



