Reinarka on the Unto Sai/ii and i'nio Oarnjifodon. 245 



generally received synonym, Umo Sat/ii, Ward. I sluill present for 

 your consideration the original descriptions and remarks of Mr. Say 

 upon the Unio Camptodon, and of Mr. Ward upon the Unio Sayii, and 

 afterward the names of such shells as are regarded by Mr. Lea, in his 

 synopsis of 1870, as synonyms of this species. 



A correct and undisputed nomenclature is the first thing necessary 

 in the study of any subject, and the most important point to be settled 

 in the pursuit of this portion of natural science. Want of uniformity 

 in regard to this has ever been the dark spot upon the body politic of 

 the shell world. Why a poor, little, innocent shell should be burdened 

 with so many names, and its moral standing materially affected in its 

 own country by long and bitter qontroversy, respecting its true and 

 lawful name, is a subject of deep interest to the conchologist ; and 

 when the shells shall each be know'n by a single name, the beauties oi 

 this branch of natural history will be more readily appreciated, gen- 

 eral interest may be excited, and couchology may become a popular 

 study. 



I shall now proceed to give you ]Mr. Say's description of Unio 

 Camptodon, Dr. Ward's description of Unio Sayii, and a few re'marks 

 thereon of my own. 



Unio r.amptodon — (Thomas Say). 



[American Conchology, part 5, plate 42. August, 1832. Specimen from New Orleans.] 



Shell moderately thin, transversely oblong-oval, a little compressed, 

 dark brownish or blackish; beaks with regular small undulations, 

 behind the middle but remote from the posterior edge, but little prom- 

 inent ; ligament slope somewhat compressed, with two distinct com- 

 pressed lines ; umbonal slope not elevated above the level of the disk ; 

 anterior margin a little prominent toward the base, and round -d ; 

 lunule large ; posterior margin prominent, extending far behind the 

 beaks and rounded ; base a little contracted in the middle; Avitliin, 

 milk white ; teeth — a single, rather long, oblique, undivided primary 

 tooth in each valve ; lateral teeth rather slender, toward the tip a little 

 arcuated. Beaks distinct from the posterior margin; lamelliform 

 teeth arcuated at tip. 



Unio Sayii — (Dr. ChaFvLes J. Ward). 



[Araei-ican Jounml of Seienca. January, 1839. Vol. a^ p. 268, Specimen from OMo.] 



Shell subrhomboidal, inequilateral, transverse, compressed; valve 



