30 



UKIO. 



QUADRATE. 



*plicatus.' Lesueur. Say. Bar. Sh. 

 c& Uat. HildP Sivain. Ghenu. 

 Han. 

 TInio Peruviana. Lam. 

 Unto rariplicata. Larti. Desh. 

 JJnio Domleyanus. Valen. 

 TJnio undidata. Desh. 

 TInio multiplicata. Desh. 

 TJnio crassus. Barnes. 

 My a plicata. Eat. 



*infucatus. Con. 



TInio securiformis. Con. 



. *Kleinianus. Lea. 



TInio liratus. Shuttleioorth. 



*nucleus. Lea. Mart. 



Napeanensis. Con. 

 TInio dorsuosus. OouJd. 



TRIANGULAR. 



*psainmoiciis. D''Or'h. Hupe. 



*foliatus.^ Hild. Chenu. Han. 

 TInio flexuosus. Con. 



*C£elatus. Con. Han. 

 *Kirkii. Lea. 



TRIANGULAR. 



*Nyassensis. Le^ 

 TInio Nyassse. 



*Aferulus. Lea. 



Sow. 



*dimotus. Lea. 



TInio SumatrensisJ^ Lea. 



Lamprej^anus. Baird & Adams. 



Oliinensis. Lea. 



OBLIQUE. 



Tientsinensis. Crosse & D. 



tortuosus. Lea. 

 TInio suhtortus. Baird & Ad. 



Swainsoni.^ Sow. Reeve. 



OVAL. 



*corrugat-us. Retzius. Speng. Lam. 



Desh. Blan. Han. 

 Mya corrugata. Midler. Chem. 



Schrot. Gmel. Wood. Dill. 



Schreib. Menke. 

 Mya rugosa. Gmel. Wood. Dill. 



Schreib. 

 Mya nodosa? Gmel. Wood. Dill. 

 Mya spuria. Ginel. Wood. Schreib. 



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

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

 Mr. Say, belie'\'ing it to be only a variety of crasstfs, so stated in Nicholson's Uncy., 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 Lesuenr's, it is Mr. Barnes's species. 



^ 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 bj^ 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. 



' The male of foliatus 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. 



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



° Mr. Sowerby substituted this name for Uniopsis radiatus and mytiloides, Hanlej', both being pre- 

 occupied. 



