ANODONTA. 21 



Var. II. Roissyi. Longer than the type, lower 

 margin rounded outwards. 



Genus III. ANODONTA. 



The members of this genus are almost toothless, as 

 the name implies. They are ovoviviparous. 



1. A. CTGNEA ([eaten by'] swans'). 



Oblong, swollen, thin, brown or green, well marked by 

 lines of growth ; ligament long and parallel to the lower 

 margin ; inside pearly, iridescent. Length two and a half 

 inches, breadth five. 



This is the largest of our freshwater mussels, attain- 

 ing an average breadth of over five inches. It is found 

 in great abundance in slow rivers, ponds, and canals as 

 far north as Perth. 



Var. I. radiata. Larger, rayed with yellow. 



Var. II. incrassata. More swollen and solid. 



Var. III. Zellensis. Broader, yellow-brown. 



Var. IV. pallida. Light yellow, wedge-shaped. 



Var. V. rostrata. Ovate, upper margin forming a 

 crest. 



2. A. ANATINA ([eaten 'by'] ducks). 



Oval, compressed, green or brown, glossy ; ligament short, 

 prominent, straight, forming an angle with the lower 

 margin. (See plate.) Scars deeper than those of the last 

 species. Length two inches, breadth three and a half inches. 



