NKW FHKSIl WATKI! A.Nl' LAND SIIKLLS. ;}1 



distinctly impressed; cavity of the shell rather deep and rounded; cavity of tlie beaks 

 rather deep and subangular; nacre salmon color and iridescent. 



Retnarks. — I owe to the kindness of Prof. Nuttall, two specimens of this pretty 

 little species, which he gave me on my last visit to England, in 1853. In outline it 

 approaches U. olivaceus, (nobis,) from Calcutta, but is a little more angular on the 

 posterior margin. It is by no means so thin in the substance of the shell, and differs 

 in the teeth, they being in the NuUallianus thicker and less lamellar. The color is 

 very different, the oUvaceu-i being pale blue, while both the specimens before me of 

 Nuttall lanm are salmon colored within and olive without, and with transverse bands. 

 There is a group of Uaiones in India, which are disposed to be bluish, and the cceruleiis, 

 (nobis,) may be considered decidedly the type. The Nnttallianns has an epidermis 

 of rather a bluish green olive, and the nacreous matter deposited in the interior of the 

 beaks of both specimens is decidedly blue. The tips of the beaks being eroded in both 

 specimens, it is impossible to say if there be undulations, but the blue hue of the 

 nacre in the beaks is very observable there. The outline of U. Keraudreni, Eydoux, is 

 nearly the same with this species; but they are evidently distinct. I dedicate 

 this pretty little species to my old friend Prof. Nuttall, who has done so much to 

 elucidate the natural history and botany of the United States. 



Unio umbrosus. pi. 30, fig. 26. 



Testa lavi, elliptic;!, subinflata, inaequilaterali ; valvulis subcrassis ; natibus promiQulis ; epidermide castanefi, 

 polita, transverse faseiata ; dentibus cardinalibus magnis, duplicibus subelevatisque ; lateralibus longis, 

 lamellatis subcurvisque ; margarita vel purpurea vel rosea et iridescente. 

 Shell smooth, elliptical, somewhat inflated, inequilateral ; valves rather thick ; beaks 

 a little prominent; epidermis chestnut brown, polished, transversely banded ; cardinal 

 teeth large, double in both valves and rather elevated; lateral teeth long, lamellar 

 and somewhat curved, nacre purple or rose color and iridescent. 

 Proc. Acad. Nat. Sci. Vol. 8, p. 95. 

 Hah. — Medellin River, Mexico. Dr. Burrough. 



My cabinet and cabinet of Mr. Anthony. 

 Diam. 1, Length 1-7, Breadth 29 inches. 



Shell smooth, elliptical, somewhat inflated, inequilateral, flattened on the sides ; 

 substance of the shell rather thick, thinner behind; beaks a little prominent; ligament 

 rather short and thick ; epidermis chestnut brown, very smooth and polished with 

 distant marks of growth and two or three rather broad, transverse, yellowish bands, 

 very obscurely rayed ; umbonial slope raised and subangular ; cardinal teeth large, 

 double in both valves, elevated into obtuse points and crenulate ; lateral teeth long, 

 lamellar, somewhat curved, the inferior division in the left valve is much the larger ; 

 anterior cicatrices distinct and well impressed ; posterior cicatrices confluent ; dorsal 



