36 



WEST COAST SHELLS 



there have been found specimens nine inches long 

 and four inches in diameter, standing perpendicu- 

 Larly in the mud. The epidermis is roughly bearded 

 near the edge of the shell, while the buried parts are 

 strongly eroded. The Horse-mussels usually grow 

 rapidly. 



Modiolus capax^ Conr., is a similar species from 

 the south, though I have grave doubts whether it is 

 really distinct from the last species. I have gathered 

 them abundantly about San Pedro. When the epi- 

 dermis peels off from the outside of the shell the 

 latter often appears of a brick-red color. 



Modiolus rectus^ Conr., the 

 Straight Horse-mussel, is shown in 

 Figure 17. The shell is long and 

 narrow, thin and delicate. The epi- 

 dermis near the hinge end is dark 

 brown and glossy; in front it is light 

 brown, with numerous chaffy hairs; 

 internally the shell is white. The 

 common length is three or four 

 inches, but a variety, flahelhis^ Gld., 

 found on the shores of British Co- 

 lumbia and in deep water off the 

 coast of California, grows to a much 

 larger size. 



Modiolus fornicatus^ Gld., the 

 Arched Horse-mussel, has a very 

 short and full shell, somewhat 

 wedge-shaped, having a breadth 

 more than half of its length. The naked shell is 

 white, though somewhat tinted, and it is normally 



Fig. 17 



