The Limpets. Tent Shells 



gray, spongy, eroded, lining polished, darkest colour in bands 

 from margin inward, centre brown and white. Scar of muscle 

 horse-shoe shaped. 



Animal with the left branchial plume, as in Acmaea, and in 

 addition a branchial cordon extending around the foot. 



The Owl Shell (S. gigantea, Gray, Lotiia gigantea, Gray), 

 is the largest and handsomest limpet on our west coast. 

 Young specimens have low and rounded tubercles set in curving, 

 radiating rows on the back of the shell. In such the colouring 

 is bright, a dark and light mottling of olive brown. The name 

 comes from the shape of the muscle scar inside the dome, which 

 has the outline of an owl. 



The shell is 3 to 4 inches long, 2 to 3 inches wide, i to 1 ^ 

 inches high. 



Habitat. — San Francisco to Panama. 



OLD WORLD LIMPETS 

 Family Patellid^ 



Shell conical, without distinct internal border; for gills 

 a row of secondary branchi.-e are substituted, set in a ring between 

 mantle and foot; jaw and radula well developed. 



A large family sub-divided upon such obscure and difficult 

 characters as the teeth of the radula, and the branchial cordon. 



Genus PATELLA, Linn. 



Characters of the family. Shell lining almost translucent, 

 somewhat fibrous in texture, iridescent. 



Patella, when young, has a nautiloid shell, but it is a remark- 

 able fact that we are entirely ignorant, in this commonest of 

 mollusks, of the transition stages which convert the nautiloid 

 into the familiar conical shell. — Cooke. 



The European limpet chooses a spot on the surface of a rock 

 as a place of residence, and there it sinks and smooths a shallow 

 pit exactly fitted to its shell. We are still guessing how the 

 creature clings with a tenacity that sustains a weight of thirty 

 pounds before the hold gives away. Back to its own place at 

 nightfall comes the individual after ranging over the rocks to 



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