- 63 — 



GEODUCK 



Panope generosa Gould 

 Plate 18, figure 2 



This huge bivalve, the largest of all known burrowing elams, has a 

 distinctive common name taken from the Indians of the north where 

 it is more common than in California. The "eo" of geoduck has the 

 sound of "oi" in oil. 



Description — The shell may reach a length of seven or more inches, 

 the valves are rather light and fragile especially at the edges, and 

 marked with broad rounded growth lines; the siphonate end gapes 

 widely to accommodate the huge united siphons. The characteristic 

 feature of the geoduck is not alone the massive siphons, which can 

 not be even approximately retracted within the shell, but the dispro- 

 portionate size of the entire body, which everywhere seems too big for 

 the shell, the valves of whicli fail to meet by an inch or more in the 

 living specimen. As a result the bulk of the animal is much greater 

 than would ])e expected from the size of the shell; weights of as 

 high as six and a half pounds are recorded. 



Habitat and habits — This is a species of sheltered water's Avitli 

 uiishii'tiiig liottom. 



Use and distribution — The goeduck is an excellent food mollusk. 

 The siphon, which is inclined to be tough, is suitable for soups anil 

 chowders while the remainder of the body is of fine flavor when fried 

 or otherwise prepared. Though its range includes the entire Cali- 

 fornia coast it is far from al)undant. In fact it was obtained at only 

 one place, Morro Bay. Because of its scarcity its economic importance 

 is negligible. 



BORERS 



The following three species represent the most conspicuous of the 

 forms burrowing into hard clay, shale and other soft rocks and known 

 as borers, rock clams, boring clams or piddocks. Though used to some 

 extent locall}^ all are of slight economic importance. 



Zirfaea gabbi Tryon 



Plate 18, figure 1 



Description — This is the largest of the borers, sometimes reaching 

 a length of four and a half inches, which represents a considerable 

 bulk, since the large siphon in a state of complete retraction projects 

 at least the length of the shell. The valves, like those of the other 

 borers, differ in the surface marking at the two ends. The anterior 

 end is greatly roughened by the development of teeth on the margins 

 of the projecting lines of growth, w^iile the siphonate end is relatively 

 smooth. The shell gapes widely at either end and the hinge area is 

 protected by a pad-like membrane which, however, lacks the plates 

 found in the two other species here described. The valves are thin 

 and easily broken. 



