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GIANT COCKLE 



Cardiiiin clatiun Sowerby 



Description— This species is even larger tliaii (Jardium quadra- 

 (joiafiidii and is reported to reach a size of six inches. It is nearly 

 ronnd and the ribs are less eonspienons than in either of the other 

 forms here treated. 



Use — It is occasionally bronght np l)y fishermen l)nt though edible 

 is of negligible importance. 



Distribution — From San Pedro southward. Found off shore 



PISMO CLAM 



Tivcla stultormn Mawe 

 Plate 6, figures 1 and 2 



This form is the most important commercially that we shall have to 

 consider, and is unique among our clams in having a distinctive 

 common name. 



Description— This large, heavy-shelled fcu-m is familiar to most 

 Californums as it is very common in the markets. The valves are 

 large, nuissive, thiek and so hard on the outer surface as to dull a file 

 rapidly. In size it exceeds most clams here considered, the gaper and 

 the geoduck being the only forms to equal it. Specimens were 

 measured having a length of seven inches and several larger examples 

 weighing over four pounds (and hence longer) are recorded, one with 

 an autlienticated weight of 4 pounds 3 ounces. The weight of those 

 exceeding the legal size of 4f inches is considerably less than this, 

 averaging about 1;^ pounds. The color of the adult is a pale buckskni 

 with some faint light purplish concentric markings, and this latter 

 color is still more marked on the siphonate end. Occasional specimens, 

 perhaps two or three in a hundred, show striking radiating stripes of 

 light jchocolate ihrsown. running from tlie umbo to the margin and 

 increasing in width with increase in size of the shell. They vary in 

 width and arrangement in different parts of the shell and in the two 

 valves. An»ong very small clams, this chocolate color is not rare, but 

 no adults entirely brown were seen though some are reported. The 

 pigment forming the rays is superficial, lying only in the outer part 

 of the shell where it is" deposited by the mantle, which apparently 

 differs, in these cases, in pigment forming power in dift'erent parts. 

 The shell is .overlaid by a thick glossy periostracum, giving the valves 

 an appearance of being varnished. In large specimens this wears off' 

 on the older portions about the umbo. The animal has a thin muscidar 

 foot of the plowshear shape and short siphons, separate at the tips. 



Habitat and habits— The Pismo clam is sharply limited to exposed 

 sandy beaches and if transplanted to the sheltered waters of bays, as 

 is sometimes done by clam diggers to ensure a supply when tides are 

 unfavorable, it does not thrive and soon dies. Here on the long beaches 

 exposed to the constant pounding of the surf which its heavy shell fits 

 it to withstand, it flourishes in what might be thought an unfavorable 

 environment. Its abundance in the early days is a matter of common 



