NIAGARA FALLS AND VICINITY 25 1 



having groove-like sculpture. There are three cardinal teeth, one 

 in the right and two in the left valve; the lateral teeth are strong. 

 Locality. Goat island. 



Genus unio Retzius. 1788 



The shell is inequilateral, elongated, rounded in front and pointed 

 behind, with a slight posterior ridge ; beaks full, slightly sculptured ; 

 surface smooth. 



"Unio gibbosus Barnes 1823 (Fig. 188). Unio nasuta 

 Lamarck (1819. Animaux sans vertebres, 6:75). Unio gib- 

 bosus Barnes (1823. Am. jour. sci. 6:262) 



Shell solid, ovate and elongated; rounded at the anterior end, 

 angulated slightly at the posterior; dorsal margin straight or nearly 

 so; ventral margin oval; muscle impressions deep and well defined; 



* s 







Fig. 188 Unio gibbosus 



teeth large and strong, the left valve having two cardinals, and two 

 laterals; growth lines coarse; pallial line deep and clear; beak's trun- 

 cated and slightly sculptured, the sculpture consisting of two or 

 three strong ridges running parallel to the growth lines. 



Found in nearly all the localities. This species seems to have 

 been the most common of the Unios. 



Genus quadrula Rafinesque. 1820 

 Shell thick, heavy and solid; teeth large and strong. 

 Quadrula solida (Lea) Simpson 1900 (Fig. 189). Unio 

 solidus Lea (1838. Phil. soc. Trans. 6:13). Quadrula 

 solida Simpson (1900. U. S. not. nuts. Proc. 22:789) 



Shell oval, solid and thick, surface marked by concentric growth 

 lines; anterior end rounded; posterior end slightly angulated; dorsal 



