20 



UN 10. 



Lea. Kirt. Potter. 



L 



QUADRATE. 



*multiplicatus. 1 



Chenu. 

 Unio heros. Say, in Disseminator. 

 Unio undulatus. Say, Am. Conch. 



No. 2. Deshayes. 

 Unio heros. Say, Am. Conch. No. 6. 



Con. 



*undulatus. Bar. Valen. Hild. Desk. 

 Unio costata? liaf. 

 Unio costatus. Con. 



*perplicatus. Con. 



*atrocostatus. Lea. 



*plicatus. Lesueur. Say. Bar. Eat. 

 Hild ? 2 Swain. 

 Unio Peruviana. Lam. 

 Unio rariplieata. Lam. Desk. 

 Unio Bombeyanus. Valen. 

 Unio undulata. Besh. 

 Unio multiplieata. Besh. 

 Unio crassus. Barnes. 

 Unio undulatus. Con. 



*infucatus. Con. 



Unio securiformis. Con. 



*Kleinianus. Lea. 



Napeanensis. Con. 



TRIANGULAR. 



*foliatus. 3 Hild. 



Unio flexuosa? Raf. 

 Unio flexuosus. Con., in text, Mono- 

 graph, p. 8. 



Con., in PI. 4, Mono- 



Unio foliatus. 

 graph. 



*cselatus. Con. 



*Stewardsonii. Lea. 



OVAL. 



*corrugatus. Retzius. Lam. 

 Mya corrugata. Mutter. Chem. 

 Schrot. Gmel. Wood. Bill. 

 Schreib. Menke. 

 Mya rugosa. Gmel. Wood. Bill. 



Schreib. 

 Mya nodosa? Gmel. Wood. Bill. 

 Mya spuria. Gmel. Wood. Schreib. 

 Mya Gardiana. Lin. Schreib. 

 Unio spuria. Lam. 

 Unio triradiata. In Museum at Paris. 

 Unio fulmineus. Phili. 

 Unio Tavoyensis. Gould. 

 Unio favidens. Benson. 

 Potamida corruyata. Swain. 



*pliciferus. Lea. 

 Unio carbonarius. 4 

 Unio plexus. Con. 



Lea. Chenu. 



*semigranosus. V. d. Busch. Phili. 



1 When I described the multiplicatus in 1830, I had had several specimens for two or three years, and was not 

 aware that Mr. Say had published a shell under the name of heros, which he subsequently abandoned as the undu- 

 latus of Barnes; but in 1834 reclaimed as heros. 



* It is extremely difficult to make out the species described by Dr. Hildreth in the American Journal of 

 Science. It appears, from a note by the editor, that he did not insert all the figures sent by Dr. H., but left out 

 those which Mr. Barnes had already, as he thought, figured in the Journal. Unfortunately, in this omission Mr. 

 Barnes's figures are not referred to, and we are, therefore, in doubt whether Dr. H. recognized, justly or not, Mr. 

 Barnes's species. 



3 The male of foliatus is certainly a triangular shell ; the female difiers in form very much, having a deep 

 inflection on the posterior basal margin. It may be doubted if this should be considered a plicate shell. I think 

 that the folds of the growth, particularly in the male shells, recpiire it to be placed here. 



4 U. carbonarius is the old and eroded of pliciferus. 



