28 WEST COAST SHELLS 



The genus Toldia resembles heda in many re- 

 spects, but the shells are generally larger and the 

 posterior end is not so prolonged or distinctly 

 marked. The hinge-teeth are V-shaped and numer- 

 ous, sometimes numbering 20 or more on a side. 

 There are a good many species found along our 

 coast, but most of them live at a considerable depth, 

 or in the cold waters of the north. 



The largest species is 

 named Toldia coo peri ^ 

 Gabb, Cooper's Yoldia, 

 and sometimes it grows to 

 a length of two or three 

 inches. The general shape 

 Fig. 12, x§ is shown in Figure 12. 



The shell is thin and com- 

 pressed, while the hinge-teeth are very numerous, 

 there being about 12 in front and 40 or 50 behind. 

 The surface has distinct concentric ridges. It is 

 found as a fossil at San Pedro, and alive off the coast 

 of central California. 



Toldia 7nonlerey crisis^ Dall, the Monterey Yol- 

 dia, has a length of 32 mm. It was dredged in Mon- 

 terey Bay, from mud where the water was nearly 

 half a mile deep. The hinge-teeth are about 20 in 

 number on each side, and the epidermis is green. 

 The genus Mallctia resembles Toldia^ but the 

 ligament is external, elongated, and prominent, 

 while in Toldia it is slight. Malletia faba^ Dall, 

 the Bean Malletia, has an elegant little shell, nearly 

 an inch long. It is smooth, ovate, inflated, with a 



