38 



UNIO. 



'TRIAXGULAR. 



liabetatus. Con. 



'''SUCCISSUS. 



Lea. 



*glaiidaceus. Lea. 



*Bigbyensis. Lea. Chenu. 



*favosus. Lea. 



*maculatus.' Con. 



*Barnesianus. Lea. Chenu. Han. 



*verus. Lea. 



*cuneolus. Lea. Chenu. 



*Clincliensis. Lea. 



*persoiiatus. Say. 



Unio pileus. Lea. Han. 

 Unio capillaris. Lea. (female.) 



*Stewardsonii. Lea. 



*biemarginatus. Lea. 



*Sowerbianus.^ Lea. Con. Kiist. Han. 



""Otbcaloogensis. Lea. 



*trigorLus. Lea. Chenu. Han. 



TRIANGULAR. 



*Eiddellii. Lea. 



*C]iunii. Lea. 



*irrasus. Lea. 



*Eajahensis. Lea. Chenu. Blan. 



*favidens. Ben. Blan. 



*stabilis. Lea. 



*iiistructus. Lea. 



Nagpoorensis. Lea. Blan. 



cyrenoides. Phili. 



^'Holstonensis. Lea. Chenu. 



*tuniescens. Lea. 



*fu]gidus. Lea. 



*Hartmanianus. Lea. 



*Taitianus. Lea. 



*solidus. Lea. Chenu. Han. 



*obliquus. Lam. Menke. Han. 

 Unio undatus. Bar. Hild. Kilst. 

 JJnio trigonus.^ Say. Con.; not of 

 Lea. 



^ Perfect specimens of Unio Ravenelianus (nobis) look so much like maculatus, that I am disposed to 

 think, when manj^ specimens of both are examined, they will prove to be the same species. Bavenelianus 

 has precedence. 



^ See note on Haysiamis, Lea, p. 41. 



^ Say and Conrad both give trigonus (nobis) as a synonym to undatus., Barnes. It is difficult for 

 me to understand why they should not at once, on comparison, be recognized as different species. The 

 trigonus is always more angular on the umbonial slope, and the undulations at tlie tijDS of the beaks differ. 

 This may be observed particularly in the J'oung and perfect specimens. If a doubt could be admitted 

 as to the difference of the form of the shell, the color of the animal in trigonus would at once settle the 

 question. It is peculiar, being red. 



Some years since, when I described this species, I deposited a specimen in the Academy of Natural 

 Sciences of this city, with its iJrojDcr name appended. Subsequently, I found the Academy had prefixed 

 the name of undatus, Barnes, to the label. There is not a doubt as to its being specifically different. 



