UNIO. 



B 

 P 



CD 



K 

 c 



TRIANGULAR. 



t/mo mytiloides. Sh. & Eat. 

 Unio undulatus. Desk. 

 Unio cordatus? Raf. 

 Unio cordatus. Con. K'tist. 

 Unio caridiacea. Gucr/'/i. 

 Mya undata. Eat. 



*plenus. Lea. 



*pyramidatus. Lea. K'dst. Chenu. 



Desk. Han. 

 Unio rubra? Raf. 

 Unio mytiloides. Con. 

 Unio cardiacea. Desk. 



*Bournianus. Lea. Chenu. 

 *Edgarianus. Lea. Chenu. 

 *Mooresianus. Lea. 



^mytiloides. 1 Raf. Swain; not of 



Desk. , 



Unio triangularis. Con. 

 Unio rubra. Con. 

 Unio caridiacea. Con. 

 Mya obliqtia. Wood. 



TUIAXGULAR. 



Uniopsis mytiloides. Swain. 



OBLIQUE. 



*Troostii. Lea. Han. 

 Unio trdbalis. Con. 



*trossulus. Lea. 

 lepidus. Gould. 



*Tigris. Per. 



Unio Tiyridis. Boury. 



*Pazii. Lea. 



*terminalis. f Bourg. Mouss. Trist. 



*tumidulus. Lea. 



cor. Con. Han. 



truncatus. Swain. Han. 

 *Bourguignatianus. Lea. 

 *dignatus. Lea. 



1 It is a matter of great doubt if this name ought to be admitted at all in this table. It was applied, 

 many years since, by the naturalists of this city, without reference to any particular specimen, but, as it 

 now appears nearly certain, incorrectly. Dr. Ward says the description and outline would "equally well 

 apply to six or eight different species." The difficulty of recognizing Mr. Rafinesque's species is well 

 illustrated in this one. Mr. Conrad, in New Fresh Water Shells V. S., considers triangularis, Raf.. as 

 the type, and gives the following names of the same author as s3Tionyms, viz., latrrali.*, .//' 

 pachostea, mytiloides, and rubra; thus charging him with making six species of one. But, what is still 

 more extraordinary, this single species (agreeably to Mr. Conrad's synonyms) is not only divided l.y 

 Mr. R. into different subgenera, but into different genera, and even into TWO DIFFERENT SVB-FAMI; 



See New Fresh Water Shells of the United States, p. 72, and Mr. Rafinesque's Monoyraphie. In Mr. Sa\ '- 

 Synonymy, triangularis, Raf., is considered to be the same as ellipsis (nobis)I Deshayes described a 

 different shell under the name of mytiloides. (Ency. Mvth., p. -24!l, Kig. 4.) I doubt from this figure if it 

 be not a complanatus. We certainly have in our rivers, occasionally, specimens of this protean >i 

 very closely resembling this figure. M. Deshayes's figure has some resetnMam-e t<> an imperfect 

 Satauus. The habitat is not known. The confusion is increased by Mr. Conrad's' subsequent attempt 

 at correction. In Monography, 1836, he makes mytiloides a type, and puts rulirn, Knf., pyramid 

 and caridiacea, GueVin, as synonyms. Subsequently, in Synopsis of 1853, mylili>i<l>:-- and frtoupvlwil 

 are both dismissed as types, and the former made synonym to clava, Lam., whMe the latter is made 

 synonym to triqueter, Raf.!! 



2 Mr. Tristam, in Proc. Zool. Soc. 1865, p. 543, says he thinks that (rrminalis and ./rW-iV>-. Hour.', 

 are the same, and that diynatut (nobis) seems to him to be identical with ti-riniimlif. luit I doubt it. 



