UNIO PHILLIPSII. 



Plate V.— Fig. 1. 



DESCRIPTION. 



Shell subovate, with concentric furrows; anterior 

 side smooth; disk with a single row of irregular 

 tubercles in the centre, some of which are elongated 

 and grooved; posterior side narrowed, with a wide 

 furrow and a few small tubercles; umbonial slope 

 straight, carinated and tuberculated; posterior slope 

 concave, indistinctly tuberculated; ligament slope 

 rectilinear, oblique; extremity direct, emarginate; 

 basal margin swelling centrally, emarginate behind; 

 umbo prominent, rather broad, flattened at the sum- 

 mit; beaks retuse; epidermis yellowish-brown, with 

 indistinct filiform rays over the umbo; within white; 

 cardinal teeth rather small, direct, double in each 

 valve. 



OBSERVATIONS. 



This handsome species is allied to U. quadridas, 

 Raf., but is very distinct, the young shell having 

 broad smooth and retuse beaks, whilst the young of 

 the quadrulus has the beaks narrowed, tuberculated, 

 pointed and curved forwards. The specimen figured 

 is from the Wabash, and is in the cabinet of Mr. 

 John Phillips, who called my attention to it as a 

 distinct species, and I have dedicated to him a small 

 tribute of respect for his talents and scientific zeal. 



