304 



WEST COAST SHELLS 



disco-triangular, fiattened, light green or brown out- 

 side, iridescent or pearly within, and has a pro- 

 nounced posterior wing. It inhabits streams and 

 lakes in the Utah, Nevada, Coast Range, Los An- 

 geles and Arizona Systems, also the western drain- 

 age of Mexico. It is found less commonly as far 

 north as British Columbia. 



A species resembling an A7iodonta and long 



Fig. 289 



classed with them is Gonidea angulata^ Lea, the 

 Pacific Naiad, Figure 289. This lacks the hinge- 

 teeth except as rudiments, is rather pointed in front, 

 somewhat triangular, and is unequally divided 

 by a carina or angle extending from the umbo 

 to the lower posterior corner of the shell. Pearly 

 within, nacre blue, pink, or yellow brown. Speci- 

 mens with ova are a brilliant co{)per color which, 

 however, soon fades after death. 



Found in the Columbia, Klamath, and Coast 

 Range Systems, usually in clay banks or beds of 

 streams. 



