NEW EXOTIC UNIONlDiE. . 381 



Ilab. — Uruguay River, South America, Prof. J. Wyman. 



My cabinet. 

 Diam. 1-2, Length 2-2, Breadth 2-8 inches. 



Shell smooth, subrotund, somewhat compressed, inequilateral, rounded before and 

 behind ; substance of the shell thick, thicker before ; beaks somewhat prominent 

 and a little inflated ; ligament rather small and dark-brown ; epidermis blackish, 

 roughly striate before and without rays ; umbonial slope slightly raised and rounded ; 

 posterior slope compressed, slightly sulcate on each valve ; cardinal teeth rather 

 small, erect, rather compressed and double in both valves ; lateral teeth rather 

 long, very much curved, and forming an arch at the plate anterior to the cardinal 

 tooth ; anterior cicatrices rather small, well impressed, confluent with the lower but 

 distinct from the upper ; posterior cicatrices rather large, confluent and very slightly 

 impressed ; dorsal cicatrices in a long row across the centre of the cavity of the 

 beaks ; cavity of the shell somewhat shallow and wide ; cavity of the beaks rather 

 shallow and obtusely angular ; nacre white and salmon color. 



Remarks. — Two specimens and a large odd valve are before me. This species is 

 closely allied to funebralis, herein described, and of course belongs to the group of 

 which Paranensis is the type. It differs from funebralis in being more inflated, in 

 having a less palleal border, in having a darker epidermis and in the cardinal 

 teeth being more lobed. Like it, one of the specimens is disposed to be salmon 

 colored, and also to have much epidermal matter deposited on the inside, in anticipa- 

 tion of erosion. In outline it is very close to variabilis, (Mya) Maton, but it has a 

 rougher aud much darker epidermis, and it is not so high in the carina of the 

 posterior slope. The superior anterior cicatrix is well impressed and separate from 

 the great anterior adductor cicatrix, — a character usual to the South American 

 species. Neither of the specimens have beaks sufficiently perfect to show costce on 

 the tips, if they belong to the species, which no doubt is the case. 



Unio Wymanii. PI. 42, fig. 289. 



Testit lsevi, antice subsulcata, quadrata, cornpressa, ad latere plauulatu. insequilaterali, postice obtuse 

 augulata, antice rotundata; valvulis suberassis, antice crassioribus ; natibus prominulis, ad apices 

 divaricate undulatis ) epidermide tenebroso-oliva, vel eradiata vel obsolete radiata ; dentibus cardi- 

 ualibus compressis, erectis, erenulatis, in utroque valvulo duplicibus ; lateralibus long'is, crenulatis 

 subcurvisque ; margarita argentea et valde iridescente. 



Shell smooth, somewhat sulcate before, quadrate, compressed, flattened at the 

 sides, inequilateral, obtusely angular behind and rounded before ; valves rather 

 thick, thicker before ; beaks somewhat prominent, Avith diverging undulations at 

 the tips ; epidermis dark olive, without rays, or obscurely rayed ; cardinal teeth 



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