CONCHOLOGICAL WRITINGS. 11 



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 Truncilla, approximating 

 to Scalenaria and Plagiola, but the hinge is like Truncilla. 



100 Sp. Unio granulatus. (Tr. g^anulata, 18'2,l.) 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. TJnio 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. 



Yar. 1. Vittafa, with black band^. 



In the Cumberland and Green Rivers, very rare ; the lai;geBt 

 Truncilla, often 2 inches, lamellar tooth crenulate, as in Tr. truncata. 

 Sp. 19. 



N. B. Besides these 26 new TJnio, I find in my notes the account 

 and figures of several others, such as U. pustulatus, U. punctatus, 

 U. scaber, U. elegans, 13. badius, U. crenulatus, &c., but not having 

 now the specimens before me, I must delay their publication. 



Of my previous species of 1820, bat few are found in Lamark last 

 edition of 1819. My U. latissima is, perhaps, his U. recta. I 

 found only 8 names, of difi'erentsp. from mine, clashing by similarity, 

 U. retusa, U. sinuata and IT. depressa. I have thus changed 

 mine in consequence. My U. retusa, 1820, is now my U. premorsus, 

 my U. depressa 1820, is my U. compressus ; my U. sinuata 1820 

 is my TI. cuUratus. 



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, 



