CONCHOLOGY. 67 



U. rostrata. U. luteola. 



U. pictorum. U. marginalis. 



U. Batava. U. angusta. 



U. corrugata. U. manca. 



U. nodulosa. U. cariosa. 



U. varicosa. IJ. spuria. 



U. granosa. U. Australis. 



U. depressa, U. anodontina. 



U. Virginianum. U. sub-orbiculata. 



U. pictorum. The Painter's Unio. PI, 8, fig. 6. 



Species oval, not auriculated, strong, anterior side rhom- 

 boid and attenuated ; the opposite side obtusely acute ; the 

 umbones somewhat warted ; concentrically wrinkled ; cov- 

 ered with a dusky green epidermis. 



U. sinuata. The crooked Unio. 



Species oval, sub-auriculated ; cardinal tooth short, not 

 lamellar or sub-striated. 



U, sub-orbiculata. The sub-orbicular Unio, 

 Species round or almost round ; cardinal tooth compress- 

 ed, elongated, and often lamellar. 



2. Hyria. Two species. 

 Easily distinguished from the Unio by a compound car- 

 dinal tooth, which slopes in an inclined position towards the 

 posterior side. They are more found in lakes than in rivers. 

 Shell solid, pearly, equivalve, obliquely triangular, auricu- 

 lated ; base truncated and straight ; hinge with two project- 

 ing teeth ; the cardinal divided into numerous divergent 

 parts ; anterior ones smaller, the others long and lamellar. 

 Hyria avicularis. Hyria corrugata. 



H. avicularis. The little bird Hyria. PI. 5, fig. 4. 



Umbones smooth and polished ; ears large, with pointed 

 terminations ; finely striated ; interior pearly, exterior of a 

 rich reddish golden-yellow colour; covered with a greenish 

 brown epidermis. 



