The Limpets. Tent Shells 



but in the British Isles it is smaller. Brown and green stripes 

 radiate from the apex, crossing concentric circles of white 

 and black on the gray ground in a more or less irregularly tesse- 

 lated pattern. The lines of growth are rather strong, and the 

 surface is finely sculptured with striae that cross each other. 

 Within the aperture there is a brown and white tesselated border, 

 then a white lining with a large owl-shaped patch of brown, 

 the muscle scar, under the apex. 



This sluggish mollusk wanders forth to feed on the soft 

 tissues of algje. It returns to its own place on the under side 

 of a rock after each excursion. 



Var. alveus, Conr., is so thin that the checkered pattern 

 is seen through the wall. The sides are compressed to fit the 

 shell to the stems of seaweeds on which it lives. The elevated 

 peak sometimes forms a forward-pointing hook. 



These, like the typical tortoise-shells, are found in cold 

 waters on both Atlantic and Pacific coasts of North America, 

 along with forms that intergrade between them. 



A. candeana, Orb., a Floridian species, has seven to nine rays 

 of black running down the gray or bufi' sides, or the black spreads 

 in more numerous, finer rays. Five lines of black cross the narrow 

 inner border. The ovate shell is depressed; the surface cut by 

 radiating striae. Length, i inch. 



Habitat. — West Florida, Bahamas. 



The west coast of the United States is particularly rich in 

 species and varieties of this genus. I will not describe all of 

 them, but select the most common and distinctive. 



The Plate Limpet (A. patina, Eschs.), modified forms of 

 which show it to be closely related to A. tesiudinalis, is the most 

 characteristic limpet of the west coast. The shell is flattened, 

 the blunt apex near the middle; the back is gray, finely tesse- 

 lated with black. The flesh is white. Length, 2 inches. 



Habitat. — Aleutian Islands to San Diego, Cal. 



The Rough Limpet (^A. scdbra, Rve.) is sculptured with 

 close, radiating, scaly ridges diversified regularlyby ribs of greater 

 size and elevation. Yellow with faint brown markings is the 

 usual colouring. The apex is low, the slopes convex. The 

 flesh is black. 



Var. limulata, Cpr., has a black band around the apex, and 

 a black border inside the aperture. The rest of the interior 



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