22 ■ DESCRIPTIONS OF 



ina<»nis, obliquis, compressis crenulatisque ; lateralibus longis, rectis laraellatisque ; margarita salmonis 

 colore tincta et iridescente. 



Shell sulcate, oblong, inflated, subemarginate, nearly equilateral, obtusely angular 

 behind ; valves thick ; beaks small, a little prominent and undulate ; epidermis yel- 

 lowish brown, striate ; cardinal teeth large, oblique, compressed and crenulate ; lateral 

 teeth long, straight and lamellar ; nacre salmon colored and iridescent. 

 Proc. Acad. Nat. Sci. Vol. 8, p. 94. 



Eab. — Cape of Good Hope. Mr. E. Verreaux. 



My cabinet, cabinets of Mr. Verreaux, Paris, and W. A. Haines, New York. 

 Diam. 1, Length 1.4, Breadth 2-5 inches. 



Shell furrowed, oblong, inflated, slightly emarginate at base, nearly equilateral, 

 obtusely angular behind ; substance of the shell thick, thinner behind ; beaks small, 

 a little prominent, with numerous small undulations at tip ; furrows transverse, rather 

 close, irregular and covering nearly the whole disk ; lines of growth distant and very 

 distinct; ligament rather long and somewhat thick; epidermis yellowish in the 

 younger specimens, but dark brown in the older ones ; -umbonial slope subangular ; 

 cardinal teeth large, oblique, compressed, crenulate, double in both valves ; lateral 

 teeth long, straight, lamellar, single in the right and double in the left valve ; anterior 

 cicatrices distinct ; posterior cicatrices distinct ; dorsal cicatrices placed on the under 

 posterior part of the cardinal teeth ; cavity of the shell deep and rounded ; cavity of 

 beak rather deep and subangular ; nacre light salmon colored and iridescent. 



BemarJcs. — I owe the possession of several specimens of this interesting species to 

 Mr. Verreaux, naturalist, of Paris, whose researches for many years in South Africa, 

 &c., has added so much to various branches of natural history. It belongs to that 

 group which I have called silicate, from the transverse furrows which exist in the 

 substance of the exterior of the shell. It is not so sulcate as Scamnatus, Morelet, 

 nor is it so much compressed. In outline and general form, it is nearly allied to U. 

 confertus, (nobis,) but is not so ventricose as that species, nor is it so angular behind. 

 It cannot be confounded with U. Gaffer, Krauss, as that species is much smaller, more 

 compressed, the form more elliptical, the teeth more tuberculose and the nacre purple. 

 I dedicate the species to that persevering traveller, Mr. Edward Verreaux. 



Unio Shurtleffianus. pi. 27, fig. 17. 



Testa minutfe plicata, elliptica, inaoquilaterali, subcylindracea, postice obtusfi angulata, antice rotundata, ad 



latus subplanulata ; valvulis subcrassis; natibus prominulis, ad apices minute undulatis; epidermide 



virido-lutea ; dentibus cardinalibus sublongis, compressis geminisque ; lateralibus longis subrectisque ; 



margarita salmonis colore tincta et iridescente. 



Shell minutely folded, elliptical, inequilateral, somewhat cylindrical, obtusely 



angular behind, rounded before and slightly flattened at the sides : valves somewhat 



thick ; beaks a little prominent aiid minutely undulated at tip ; epidermis greenish 



