164 PROCEEDINGS OF THE ACADEMY OP 



Remarks. — A rather unusual outline, and more like some South American 

 species tlian our own, except humerosus (nobis), which it is closely allied to. 

 The exterior is very much and coarsely striate. 



Unio Roanokoides. — Shell smooth, very wide and slightly curved at basal 

 margin, compressed towards the beaks, rounded before and beliind ; beaks 

 slightly raised, well advanced towards the anterior margin ; cardinal teeth 

 rather large, very much striate ; lateral teeth very long, lamellar and slightly 

 curved. 



Length 2-6, breadth 4-8 inches. 



Remarks. — The form of this species is very unusual, and it is nearest in out- 

 line to Roanokensis and macer (nobis). A portion of the nacre remains on the 

 specimen, but there is no appearance of rays on this or any other of these spe- 

 cimens. The anterior portion is remarkably compressed for a Unio; this 

 character somewhat applies to others which accompanied it. 



TJnio ligamentinoides. — Shell smooth, elliptical, very much compressed, 

 very inequilateral, angular behind and rounded before ; beaks slightly raised ; 

 cardinal teeth compressed : lateral long, lamellar and curved. 



Length 2-3, breadth 3-5 inches. 



Remarks — The outline and general appearance of this shell is nearly that of 

 a compressed male Ugamentinus, Lam., but rather more arched above. The 

 curves are regular, and no doubt that in a perfect state it must have been 

 attractive as its prototype now existing is. 



Unio alatoides. — Shell alate, smooth, subelliptical, very much compressed, 

 inequilateral, rounded before and behind; beaks raised; cardinal teeth 

 oblique and compressed ; lateral teeth long, large, lamellar and very slightly 

 curved. 



Length 2-9, breadth 4-2 inches. 



Remarks. — A single specimen only is before me, and this by no means per- 

 fect. It is very closely allied to alatus, Say. The anterior dorsal portion of 

 one valve is gone, and that of the other valve is crushed, but the posterior por- 

 tion is in a very good state, showing a perfect and deep mould of the large, 

 regular, lamellar lateral tooth, over which the posterior dorsal portion of the 

 disk extends into a well-defined wing, which was connate above, but not ex- 

 tending so high as in alatus. 



Anodonta granbioides. — Shell smooth, elliptical, very much inflated, ventri- 

 cose, obtusely angular behind, obliquely rounded before ; beaks submedial, 

 flattened at the tips, but very much inflated on the umbos. 



Length 3-3, breadth 4-9 inches. 



Remarks. — This species is more like grandis^ Say, than any other of our 

 western Anodontse. It is about the same size, and of very nearly the same out- 

 line. Both the valves are present, and in their natural relevant positions. The 

 umbos are much inflated, but not so much as the other species {^corpuleMoides) 

 herein described. 



Anodonta cobpulentoides. — Shell smooth, rotundo-elliptical, exceedingly 

 inflated, very ventricose, obtusely angular behind, rounded before ; beaks sub- 

 medial, flattened at the tips, but excessively inflated on the umbos. 



Length 3-6, breadth 6 5 inches. 



Remarks. — This species is so nearly like corpulenta, Cooper, that I have no 

 hesitation to consider it nearest in outline and form to that remarkable species, 

 described by the late Judge William Cooper, and which inhabits the Lake of the 

 Woods, and other north-western waters. There is no mistaking the peculiar 

 great enlargement of the umbos of this species being analogous to corpulenla. 

 There are two imperfect specimens before me, but the larger one has the ante- 

 rior half of the right valve and posterior half of the left valve, which enables 

 me to make a nearly correct description and measurement. 



[June, 



