— 55 — 



maintained by the huge siphons. Though the elam itself is usually 

 imbedded in fairly permanent ground the siphons, perhaps because of 

 their size and strength, are much less sensitive than tbose of most other 

 species to drifting mud or sand and often the newly extended siphon 

 will carry on its tip a plug of sand that it has forced out of the burrow. 

 The siphon is closed at the will of the clam by two valves of horny 

 epidermis, which serve as protection against marauders inanimate and 

 animate. ' This special protection is not found on any other species here 

 treated. The siphons still remain the most vulnerable part and are 

 apparently eaten by fish that are ciuite unable to dig up the entire 

 clam. Thompson reports* that siphon tips are connnon in the stomachs 

 of the halibut and has informed the writer that these were chiefly from 

 the gaper, as shown by the presence of the characteristic hard plates. 

 Buried at such a depth, it would be hard to discover them unless 

 they betrayed themselves, which they do by their habit of squirting out 

 periodically a strong .jet of water two or three feet into the air, 

 especially, "however, when alarmed. A bed of such clams may always 

 be distinguished by this peculiar habit, or rather by the marked develop- 

 ment of this habit, which is more or less widely spread among clams. 



They are found both in the protected waters of bays and river 

 nu)utlis and along the rocky beaches of the outer coasts. Their large 

 siphons and the depth at which they live seem to fit them to survive 

 wherever they are able to find a firm and stable beach, whether it is 

 rocky or not, "but they are also ahle to dwell in the mud or firmer sand 

 where they may remain more continuously in the water than My a, the 

 soft-shell. So they are to be sought along the edges of channels near 

 low tide line, and also on the more exposed beaches where the shore line 

 is firm and permanent enough. They do not seem to be able to with- 

 stand the low salinity which 3Iya is able to endure, however, and hence 

 seem to be found near the entrances of bays or the mouths of channels. 

 Distribution— Although widely distri])uted it is particularly 

 abundant at certain points, among which may be mentioned Uhlrich's 

 (a ranch near the California-Oregon boundary). Crescent City, Wilsons 

 Creek, Patricks Point, Trinidad, Humboldt Bay, Bodega Bay, Tomales 

 Bay, Drakes Estero, Bolinas Bay, Elkhorn Slough (Monterey Bay), 

 Morro Bay, Anaheim Slough, False Bay. 



In North Humboldt Bay this clam is distributed over almost tlie 

 whole available area save the most northerly part, in which Mya is 

 abundant. It is found more especially on the central tidal flats, nearer 

 the entrance than Mya. In South Humboldt Bay it occupies about 

 the same relative position, not being found in the extreme southern 

 end. The narrow central channels are of course in great part bare. 

 None were found in the Eel River sloughs. In Bodega Bay the area 

 of the beds is small, including only the central tide lands near the 

 channels. There are a few beds on the outer coast between Bodega 

 and Tomales bays. In Tomales Bay the principal l)eds lie between 

 ^ Sand Point and "Toms Point, although they are found generally with 

 the rock cockle, Paphia staminca. In Bolinas Bay they are not 

 numerous. In Drakes Estero there was a small bed inside the eastern 



*A Preliminary Report on the Life-History of tlie Halibut. Report of the British 

 Columbia Commissioner of Fisheries, 1914, p. N 94. 



