30 



UKIO. 



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QUADRATE. 



*plicatus. 1 Lesueur. Say. Bar. Sh. 



<;£• i?«£. Hild? 2 Swain. Chenu. 



Han. 

 Unio Peruviana. Lam. 

 Unio rariplicata. Lam. Desk. 

 Unio Dombeyanus. Valen. 

 Unio undulata. Desk. 

 Unio multiplicata. Desk. 

 Unio crassus. Barnes. 

 Mya plicata. Eat. 



*infucatus. Con. 



Unio securiformis. Con. 



*Kleiniamis. Led. 



Unio liratus. Sliuttleworth. 



*nucleus. Lea. Mart. 



Napeanensis. Con. 

 Unio dorsuosus. Gould. 



TRIANGULAR. 



*psainmoicus. D'Orb. Hupe. 



*foliatus. 3 Hild. Chenu. Han. 



Unio Jlexuosus. Con. 



*ca3latus. Con. Llan. 

 *Kirkii. Lea. 



TRIANGULAR. 



*Nyassensis. Lea. 

 Uriio Nyassse. Soiv. 



*Aferulus. Lea. 



*dimotus. Lea. 



Unio Sumatrensis.* Lea. 



Lampreyanus. Baird & Adams. 



Ckinensis. Lea. 



OBLIQUE. 



Tieutsinensis. Crosse & D. 



tortuosus. Lea. 

 Unio sublortus. Baird d' Ad. 



Swainsoni. 5 Sow. Reeve. 



OVAL. 



*corrugatus. Retzius. Speng. Lain. 



Desk. Blan. Han. 

 Mya corrugata. Milller. Chem. 



Schr'dt. Gmel. Wood. Dill. 



Schreib. Menke. 

 Mya ru/josa. Gmel. Wood. Bill. 



Schreib. 

 Mya nodosa? Gmel. Wood. Dill. 

 Mya spuria. Gmel. Wood. Schreib. 



1 A difficulty exists in the minds of some naturalists as to whom this name properly belongs, and it 

 is often given to Mr. Say. Mr. Lesueur gave the first specimen obtained to Mr. Say under this name ; but 

 Mr. Say, believing it to be only a variety of crassus, so stated in Nicholson's Ency., Am. ed. It still, 

 however, kept the name of plicatus, Lesueur, without any description, until Mr. Barnes, in Am. Jl. of 

 Science, 1823, p. 120, described it as Lesueur's. Therefore, if not Lesueur's, it is Mr. Barnes's species. 



2 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 foliat us is certainly a triangular shell; the female differs 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, require it to be placed here. 



4 Sumatrensis being preoccupied by Dr. Dunker, I change the name to dimotus. 



6 Mr. Sowerby substituted this name for Uniopsis radiatus and mytiloides, Hanley, both being pre- 

 occupied. 



