3. U. ovatus, 



OF THE FAMILY OF NAIADES. 



Say*, 



( ovata, 

 ( ovata, 



4. U. 



cartosus, 



Sayf, 



lutcola, 

 canosa, 

 crassus (old){, 

 carinatus (rayed), 

 ellipticus (young), 



417 



Lain. 

 Valenciennes. 



Lam. 

 Lam. 

 Say. 

 Bar. 



Bar. 



therefore, with the rules of nomenclature, I have inserted the name of complana- 

 tus to the shell described by Mr Say under the name of purpureus. 



* Dr HiUlreth, in describing this species of Say, says, " I think it a near rela- 

 tion of the gracilis ," and, when describintr the gracilis, he says, " The contour 

 of the shell, independent of the wing, is much like that of the alatus." In the lat- 

 ter he is r i lt f i r - I > • J t in the former remark altogether Wrong. 



Donovan, DHlwyu, Maton and Racket, and some other British writers have 

 made use of this name for a Unto resembling the pictorum. 1 have thought it bet- 

 ter, however, to retain Mr Say's name for his species, which is totally different, 

 being satisfied that the British shell is only a variety o[ pictorum. 



t This is probably the only species yet known to be common both to the Wes- 

 tern and Atlantic waters. 



| Crassus is omitted in this catalogue, believing that several other species, and 

 those onl they were ponderous, have been described under tins name. 



Mr Say's crassus (See; Am. Conch, plate i, lit;, s,) is evidently an old and ponde- 

 rous cariosus, and he considered the u pticatut" as a variety. Mr Barnes's eras- 

 sus is an old and thick ju rurinnus, as is most likely Lamarck's crux.tirfcns. The 

 giganteus of I)r MitchiQ's collection is aba s peruvianus, which occurs in some of 

 our western waters of a larger BUM and more ponderous than any species wc 

 know of. 



§ This species was first described by Say in the American Conchology a 



