— 38 — 



eonspieuous limule and in both the concentric growth lines are more 

 marked than the ribs. They ditfer in the number of the concentric 

 ridges wliieh are crowded in C. uudatella and more widely separated in 

 C. succmcta. In the former the ribs are everywhere very inconspicuous 

 while in C. succincta they the more marked at the siphonate end, thus 

 approaching C. fluctifraga. 



Habitat and habits — Tliese species are similar to Paphia in their 

 general habits, being found in bays in firm sand or sandy mud not too 

 frequently disturbed by waves or strong tidal currents. As might 

 be expected from the short siphons they do not burrow deeply, in fact 

 the siphonate end of the shell may often be seen at the surface of 

 the sand and the cockle thus picked up without any digging. In some 

 cases they were observed at the side of a burrow belonging to another 

 species. The Paphias found with them usually burrow to a depth of 

 several inches. 



Use — In the Los Angeles markets they rank next after the Pismo 

 and rock cockle {Paphia) in importance and there are known as hard- 

 shell cockles in contrast to the more brittle Paphia which is called a 

 soft-shell or paper-shell cockle. They are used extensively with Paphia 

 in Los Angeles and San Diego by the restaurants for chowders and 

 soups. The flavor is excellent, though because of the flatter and 

 thicker shell the proportion of meat is not as large as in Paphia. 



Distribution — The Chiones are distinctly Southern forms, ranging 

 from San Pedro into Mexico. C. undatella and C. succincta were 

 obtained at Anaheim Slough, Newport Bay and San Diego; no speci- 

 mens of C. fluctifraga were collected, though shells were found at 

 San Diego. 



THIN-SHELLED COCKLE 

 Paphia tenerrima Carpenter 

 Plate 10, figure 1 



Description — This species reaches a fairly large size (3 to 4 inches) 

 in this exceeding the following form, from wdiich it may be told by 

 the more elongated outline and the faint radial ribs which are less 

 conspicuous than the concentric growth lines. 



Distribution and use — Though of wide distribution this species 

 does not appear to be abundant in California. Shells were obtained 

 at Oceano (P. W. W.) and living specimens just south of Pital Point, 

 Ventura County (C. H.), but it can not be considered as an economic 

 species. 



ROCK COCKLE 



Paphia staminea Conrad 



Plate 10, figure 2 



Other names — Little-neck; hard-shell; Tomales Bay cockle; rock 

 clam. 



Description — The rock cockle is a clam of moderate size, seldom 

 exceeding three inches in length, with deeply arched valves so that the 

 whole animal is rounded in form and of fair weight for its size. The 



