- 57 — 



brought in by the white men, the Indians adopting the latter 's name 

 for it at the time. An old olam digger in Humboldt Bay, who had 

 lived there since before 1868, could not rememl)er having seen them 

 until some years later than the time of the supposed introduction into 

 San Francisco Bay. 



Description — The soft-shell clam may reach a length over five 

 inches though the majority are smaller. The shell is light and brittle, 

 oval in general outline, with the siphonate end more pointed than the 

 anterior. The color is commonly whitish, tinged gray by the thin 

 periostracum, though it may be nearly black or rusty red from staining. 

 The cartilage is internal and the cartilage pits are very unequal, that 

 on the left being located on a conspicuous projecting tooth (see 

 plate 17, figure 2). As this arrangement is found in no other clam 

 except Platyodon it will usually serve to identify this species. 



Habitat and habits — Mya arenana is not found in beaches open 

 to the sea. As an individual increases in age, it loses its ability to move 

 with celerity and hence to care for itself when exposed. As a conse- 

 quence storms which shift and overturn the beaches are fatal to the 

 larger clams. Neither is it capable of renewing its communication with 

 the surface of the ground when its siphon hole is choked by shifting 

 sand or gravel, and it is dependent for its food on the minute particles 

 brought in with the water through its siphons. The localities in which 

 it is found are, therefore, those w^^ll protected and with a somewhat 

 firm, or tenacious soil, in which a hole is semipermanent. As is the case 

 with other clams, the water from which it strains its food must not 

 be stagnant, but moving and full of minute life. Further than that 

 it is not particular, for the water may be brackish or slightly salty, and 

 the temperature may fall below the freezing point, yet be suitable if it 

 yields food. Bearing these -things in mind, the distribution should 

 be easy to understand. 



Distribution — The species is found in all the favorable estuaries, 

 baj's, river mouths and closed lagoons north of San Francisco on our 

 coasts. Outside of San Francisco Bay the ground occupied is small in 

 area, in comparison with the great extent of coast line. There are 

 no great flats similar to those of the Atlantic coast, no great bays with 

 extensive tidal areas. Just as the continental shelf is narrow and 

 steep, so is the shore line narrow and open. Beds are found in the 

 following localities : Lake Earl, Humboldt Bay, Big and Stone lagoons, 

 in the mouths of the Eel, Big, and Navarro rivers, in the mouth of 

 Ten Mile Creek, in Bodega Bay and Drakes Estero. 



1. I-?ke Earl. The large closed lake north of Crescent City called Lake Earl 

 has been said by a number of the local inhabitants to possess "razor clams." It is 

 occasionally opened by the breaking through of the sand spit separating it from the 

 ocean. When thi« occurs clams are said to exist on a limited portion of the shore. 

 That this is Mya admits of no doubt, because of the presence of shells on the shore 

 line, and from the nature of other closed lagoons on the coast. The bed is of course 

 of no importance at present, as it is not subject to tidal flow, and the clams are 

 small. If in time the lake is opened artificially, the beds will prove of some value to 

 local users. The beds lie between Lake Earl and Lake Talawa. 



2. Humboldt Bay. As may be seen by reference to the map, the bay is formed 

 of two portions, called locally North Bay and South Bay. The northern part of the 

 bay was at one time supplied with fresh water from Mad River, but the channel 

 has since shifted and its mouth is now merely a slough. The bay is for the most part 

 very shallow and at low tide the greater portion of the bottom is exposed save in 

 the winding channels. These extend to \he mouth of Mad River on the north 



