CONCHOLOGICAL WRITINGS. 17 
olivaceous, with narrow black lines, inside incarnate, iridescent. 
Length 3-4, diameter 1-3, axis 2-5 of the breadth. Apex not 
prominent. 
In the river Kentucky, about one inch, I have called it perplexing, 
because it deviates much from the other Zruncilla, approximating 
to Scalenaria and Plagiola, but the hinge is like Truncilla. 
- 100 Sp. Unio granulatus. (Tr. granulata, 1821.) Shell thick, 
subtriedral, very much swelled, rounded below, posterior truncature 
nearly flat, subtesselate, granular ; outside smooth, olivaceous, with 
broad blackish bands, inside bluish white. Length 1-2, diameter 
1-2, axis 1-3 of the breadth. Apex slightly cordate. 
In Salt river, rare, above one inch. Nearest to Tr. Triqueter, 
but less cordate, less tesselate, with granulations instead of warts 
behind. Not flexuose below, as Tr. truncata. Lamellar tooth 
very short. 
101 Sp. Unio metaplata. (Tr. do., 1822.) Shell thick, subtried- 
ral, much swelled, broad and curved below, posterior truncature 
nearly flat, hardly tesselate, subgranular above; cuticle yellowish, 
inside bluish white. Length 3-4, diameter 5-8, axis 2-5 of the 
length. Apex deeply cordate. 
Var. L. Vitlata, with black bands. 
In the Cumberland and Green Rivers, very rare; the largest 
Truncilla, often 2 inches, lamellar tooth crenulate, as in 7’. truncata. 
Sp. 19. F 
N. B. Besides these 26 new Unio, I find in mynotes the account 
and figures of several others, such as U. pustulatus, U. punctatus, 
U. scaber, U. elegans, U. badius, U. crenulatus, &e., but not having 
now the specimens before me, I must delay their publication. 
Of my previous species of 1820, but few are found in Lamark last 
edition of 1819. My U. latissima is, perhaps, his U. recta. I 
found only 3 names, of differentsp. from mine, clashing by similarity, 
U. retusa, U. sinuata and U. depressa. I have thus changed 
mine in consequence. My U. retusa, 1820, isnow my U. premorsus, 
my U. depressa 1820, is my U. compressus; my U. sinuata 1820 
is my U. cultratus. 
Lamark and myself gave feminine terminations to our Unios ; they 
are now generally made masculine, as I do here; but this difference 
is of little account. 
The comparative proportions of the length, breadth, diameter, 
