CONCHOLOGICAL WRITINGS. 15 
G. OBLIQUARIA. 
89 Sp. Unio calendis, (Oblig. calendis.—1821.) Shell thick and 
swelled, rounded, subtruncate behind, surface with broad flat wrinkles. 
Length 7-8, diameter 1-2, axis 1-5 of the breadth : outside yellowish, 
inside iridescent and uneven. 
In Dick river, &c. Fine sp. beautiful nacre, rare, 2 inches. Near 
to U. cyclips, but smaller, less round, lamellar tooth quite oblique, 
slightly curved as in the Plagiola, cardinal tooth striated ; proba- 
bly a Sintoxia. 
90 Sp. Unio Venus, (Obliquaria Venus.—1820.) Shell oval 
elliptic, thick and swelled, truncate behind with transverse wrinkles, 
outside nearly smooth, of a reddish chesnut colour, inside lilac irides- 
cent. Length 3-4, diameter 1-2, axis 1-3 of the length. 
In the Kentucky and Cumberland, very rare, 3 inches wide; the 
prettiest of all the Unios, resembling a Venus. Lamellar tooth thick 
erose obliqual. My Unio E£lliptica sp. 8, is very near to this; both 
are of S. G. Aximedia. 
91 Sp. Unio plateolus, (Obliq. ditto. 1823.) Shell rather thin, 
broad, elliptic lanceolate, attenuate and subacute behind, very com- 
pressed or nearly flat, outside brown nearly smooth, inside bluish. 
Length one half, diameter and axis 1-5 of breadth. 
At the falls of the Cumberland. Small, 2 inches, rare. Akin to 
U. cuprea. Cardinal tooth small, bilobe, lamellar obliqual short. 
92. Unio teneltus, (Obliq. ditto. 1822.) Shell elliptic thin, nearly 
equilateral, quite flat, margin erose, outside minutely striated, oliva- 
ceous with square green spots, inside bluish. Length 4-7, diameter 
1-7, axis 3-7 of the breadth. 
Exceedingly rare, seen only once in a stream of the Knob-hills of 
Kentucky. Size one inch. It is an Aximedia which is to be aS. 
G. of Obliquaria. Lamellar tooth obliqual very short, cardinal 
bilobe small as in Leptodea. 
93 Sp. Unio bicolor, (Obliq. ditto. 1821.) Shell thick elliptic, 
lanceolate, attenuate and subtruncate behind, with an obliqual ridge, 
outside brown nearly smooth, inside yellow above, white beneath. 
Length 1-2, diameter 1-3, axis 1-5 of breadth. 
In Kentucky river, 3 or 4 inches, akin to U. dilatata, but smoother 
inside, different nacre, axis more anterior: more rare and beautiful. 
Lamellar tooth obliqual thick.—The U. dilatata is however also an 
Obliquaria and may be called Obl. violacea. 
