68 



5IARGAEITANA, 



s 



a 



w 



H 

 O 



— 

 S3 



f TRIANGULAR. 



*Curreyana. Lea. 



*unctulata. Say. Lea. 



Unio undulata. Jay. Han. 

 Alas, undulata. Say. Bar. Swain. 

 Gould. Kiist. Adeems. Linsl. 

 Dekay. Migh. 

 Alas, sculptilis (junior). Say. 

 Strophitus sculptilis. Stirnpson. 



(Agass. MSS.) 

 Myei undulata. Wood. 

 Unio hians. Valen. 

 Unio glabratus. Sow. 

 Uniopsis radiata. Swain. 



*triangulata. Lea. 



OVAL. 



*Tombigbeensis. 



Lea. 



*Raveneliana.' Lea. 



Alasmodonta Raveneliana. Chenu. 

 Unio Swanaoensis. Hem. 



*Elliottii. Lea. 



E- 



z 



OVAL. 



*elliptica. Lea. 



*Georgiana. Lea. 



M. Etoioahensis. Lea. 

 Alasmodonta impressa. Anth. 



radiata. 2 Con. Lea. 

 Alas, radiata. Con. 

 Unio radiata. Han. 



Pfeifi'eriana. Bern. 



Kirtl. 

 Lea. Han. 



*calceola. 3 Lea. 

 Unio calceolus. 



Chenu. 

 Unio triqueter. Sh. <£• Eat. 

 Alas, marginata.* Say. 

 Alas, truncata. Con., not of Say 

 Calceola angulata. Swain. 



OBLONG. 



*Alabamensis. Lea. 



*quadrata. Lea. 



Desk. 



1 It has been supposed that this might be the Alas, marginata, Say, but in a specimen received from 

 Prof. Troost, and returned to him, I found the beaks to diner essentially, the undulations being small 

 and numerous at the tip. It differs also in the teeth and other characters. 



2 This shell, in the teeth, except in the size of them, very closely resembles the Alas, edentula, Say — 

 An. areolatus, Swain. Although in both these shells there is a small cardinal tooth, in all their other 

 characters they so closely resemble the Anodonlse, that it is a matter of doubt with me as to the propriety 

 of separating them from that genus. An examination of the animals, when satisfactorily dissected, may 

 show the necessity of placing them both, notwithstanding their possessing small cardinal teeth, with the 

 Anodontee. Swainson, in his Malacology, refers to radiata as his Uniojosis radiata; but this must be an 

 error. I think his shell is a thick var. of Marg. undulata, such as comes from Canada. 



3 In my Memoir in the Trans. Am. Phil. Soc, vol. iii. p. 420 (p. 34 of "Observations on the Genus 

 Unio"), I mention this shell as being closely allied to the genus Alasmodonta of Say. In this Synopsis, I 

 have deemed it better to transfer it to the subgenus Margaritana, as the lateral tooth is observable in 

 very few individuals. Deshayes says it is between Unio and Alasmodonta. 



* Mr. Say, in his Synonymy, makes calceolus and marginata the same. I am surprised at this, as 

 their characters, in many respects, are very different, and I have never heard it even suggested before 

 that they could be confounded. 



