188 NEW UNIONID^ OF THE 



nearly covered with rows of nodules ; cardinal teeth rather large, compressed and 

 sulcate ; lateral teeth rather long, somewhat thick, oblique and straight ; anterior 

 cicatrices distinct, rather large and well impressed; posterior cicatrices confluent, 

 large and slightly impressed ; dorsal cicatrices placed under the plate and on the 

 base of the cardinal tooth ; cavity of the shell rather shallow and wide ; cavity of 

 the beaks deep and acutely angular ; nacre silver white, sometimes rose color and 

 iridescent. 



EemarJcs. — I have, four specimens before me. The largest was received many 

 years since from Mr. J. C. Ward, with a doubt as to its being metanever, Raf. His 

 note says, " I have two others in my collection, one much larger and the other 

 smaller than this, besides which I have seen three others, all of which possess 

 exa'ctly the same characteristics. Is it not sufficiently distinct to erect it into a new 

 species ?" Within the last year I have, from three other naturalists, received three 

 specimens from other habitats. These satisfy me that Mr. Ward's suggestion was 

 correct, and I have great pleasure in dedicating it to my deceased friend, who was an 

 ardent lover of nature and a liberal gentleman. The specimen from Mr. Anthony 

 is marked " Tennessee," but Dr. Hartman, on seeing this specimen, thinks he 

 recognises it as the specimen which he gave Mr. Anthony from the same habitat 

 (Coal River, Virginia) with his own. They have precisely the same appearance, 

 and there may have been some inadvertence as to the label from Tennessee. I 

 have never received it from that State. It is very closely allied to metanever, Raf., 

 and I have had great hesitation in separating it, but the absence of regular tubercles 

 on the umbonial slope is a marked character and constitutes the chief difference. 

 The outline is rather more quadrature, and it always is much more compressed. 

 The specimen from Iowa has a pinkish tinge, very different from the silver white 

 of the others. The arrow-headed marks are of the same form and green color as 

 in metanever, but in all these specimens they are smaller. 



Unio Higginsii. PI. 24, fig. 258. 



Testa lcBvi, obliqua, ventricosa, valde iiiaequilaterali, antice rotundata; valvulis percrassis; natibus 

 valde proniinentibus, tuiuidis incurvisque; epidermide virido-oliva, polita, valde radiata ; dentibus 

 cardiualibus niagnis, crassis, erectis, crenulatis, in utroque valvulo duplicibus ; lateralibus sublongis, 

 percrassis subrectisque ; margarita, vel alba vel salroonis colore tincta. 



Shell smooth, oblique, ventricose, very inequilateral, rounded behind ; valves 

 very thick ; beaks very prominent, swollen and incurved ; epidermis greenish olive, 

 polished, very much rayed ; cardinal teeth large, thick, erect, crenulate and double 

 in both valves; lateral teeth rather long, very thick and nearly straight; nacre 

 white or tinted with salmon color. 



Proc. Acad. Nat. Sci., 1857, p. 84. 



Hob. — Muscatine, Iowa, Mr. Prank Higgins. 



