anatinidjE. 359 



Species of Cryptomya. 



Californica, Conr. Mindorensis, Adams and Reeve, 



decurtata, A. Adams. Philippinarum, A. Adams. 



decussata, Desh. princeps, A. Adams. 



elliptica, A. Adams. semistriata, Hanley. 



Fam. ANATINID.E. 



Mantle-margins united ; siphons elongate, generally more 

 or less separate, the orifices fringed ; mantle with a small 

 valvular aperture under the siphons ; gills pinnate, ap- 

 parently one on each side, the outer lamina prolonged 

 dorsally beyond the line of attachment. Foot more or less 

 linguiform. 



Shell thin, usually inequivalve, gaping at the hinder ex- 

 tremity, interior nacreous, surface often granular, scabrous, 

 or hispid, beaks often fissured. Hinge-teeth rudimentary; 

 ligament external, thin ; cartilage internal, in a pit in each 

 valve, usually furnished with a free ossicle. Muscular im- 

 pressions faint, the anterior elongated ; pallial line usually 

 sinuated. 



In the Anatinida the mantle of the animal is closed, 

 except where the linguiform foot protrudes, the siphons 

 are moderately long, with fringed orifices, and a single 

 branchial lamina, only, appears to be developed on each 

 side. The hinge of the shell is usually without teeth 

 properly so called, but is provided with a spoon-shaped 

 plate or process, and a movable testaceous ossicle con- 

 nected with each valve by an internal cartilage. The surface 

 of the valves is usually rough or hispid, with large cal- 

 careous cells arranged in lines, and is covered with an 

 epidermis ; the interior is more or less pearly and nacreous. 



