HANNIBAL : CALIFORNIA^ FRESHWATKR JIOLLUSCA. 173 



Tennessee River and tributaries above Jackson County, Alabama 

 {fide Jas. Lewis), Amei'ican Province. 



Apparently a northern sub-species of armigcra. 



Pleurockra (Io) canalicclatum nobile (Lea). 

 Jfelania nohilis, Lea, 1845 ; Io SpiUinanii, Lea, 1861 ; /. variahiUs, 

 Lea, 1861 ; /. nodosa. Lea, 1861 ; /. viodeitta, Lea, 1861. 



Shell similar to cannliculatum but larger, a sub-cariuate nodose 

 peripliery developed on the body-^rhorl, aperture produced into a 

 short gyrate canal; eanaliculatuin stage passed during late adolescence ; 

 habitat streams. 



Little Tennessee and Tennessee llivers, Alabama, American 

 Province. 



A poorly marked southern race of canaliculatum. 



Genus Ambloxtjs (Rafinesque). ^ 

 Buccinnm (sp.), Gmclin, 1788 {B. Virginicnm, Gmel.) ; Paludina 

 (sp.). Say, 1819 {B. Virginicum, Gmel.); Melanta{s]).), Say, 1824 

 (B. Virginicum, Gmel.) ; Amhloxus, llafinesque, 1831 {Melania 

 ( Amhloxus) rugosa, E,af . = B. Virgi7iiciim, (imel.) ; Uemisiniis (sp.), 

 H. & A. Adams, 1854 {M. bullosa, Gld. = M. plicifer a, Jjea) ; 

 Pachgcheilus {PachycMlus, Lea, era.) (sp.), H. & A. Adams, 1854 

 {M. simplex, Say = B. Virginicum, (Jmel.); Potadoma (sp.), H. & A. 

 Adams, 1854 [31. depygis, Say = B. Virginicum, Gmel.); JElimia 



^ While no mention of previous pubUcations is made, it would appear at first 

 glance that Amhloxus, Eafinesque, 1831, is a lapsus for Ambloxis, 

 Eafinesque, 1818, under which two species, ^4. ehurnea and ^4. ventricosa, 

 were named but not described. However, it would take a deal of imagina- 

 tion — more than the writer possesses — to fit one of the slender Pleurocerids 

 described in 1831 to the diagnosis of Ambloxis, 1818, which was doubtless 

 intended for some Viviparoid. This is borne out by the fact that in 1865 

 Binney, in the third part of his Land and Freshiuater Shells of North 

 America, figured Ambloxis major or Lymnea ehurnea and Lymnula 

 ventricosa from Rafinesque's manuscript, referring them to Melantho 

 (= Campeloma) decisa as synonyms. Eafinesque must be credited with 

 a considerable amount of acumen in recognizing genera ; his groups for 

 homogeneity were fully up to the standard of the time and in this family 

 about equal to any work that has ever been done. It seems unreasonable, 

 therefore, to accuse him of referring a vertically plaited syntonic form of 

 Buccinnm Virginicum, Gmel., to a genus of Lioplacidae. Rafinesque has 

 Amblema, Ainhlotrema, A?nblasmodon, Ambloxis, and, according to Binney, 

 Amhlostoma, so that Amhloxus is evidently another formed on the same 

 favourite plan, though it is unfortunate that he ran out of desirable 

 etymological combinations of acutus before this was named. The 

 confusion of these two is merely the outcome of the notorious carelessness 

 of this author in his writings, but cannot affect the status of Amhloxus, 

 1831, which was given to include two species, of which the first is 

 certainly recognizable and the second doubtfully so. Amhloxus and 

 Ambloxis are sufficiently distinct to stand side by side nomenclaturally, 

 but occurring as they do in allied groups from the same region there is 

 opportunity for confusion on that score. However, Ambloxis, Eafinesque, 

 1818, has no status, and Ambloxis, ' Eafinesque,' Binney, 1865, stands as 

 a synonym of Campeloma, leaving the field clear for Amhloxus, Rafinesque, 

 1831 



