HANJiTIBAL : CALIFOENIAN FRESHWATER MOLLUSCA. 169 



interposing unnecessary changes in the existing nomenclature, thus 

 eliminating them as possibilities for future disturbance. One of tbe 

 most knotty problems has been the recognition of Hafinesque's 

 genera. The English language is not forceful enough to adequately 

 express the feeling of the systeraatist who has to judge these crimes 

 in the name of science. 



Genus Pleurocera, Eafinesque. 



Pleurocera, Rafinesque, 1818, 1819 (generic diagnosis only) ; 

 Pleurocera^ Rafinesque, 1820 {P. verrucosa, Raf.) ; Melania 

 (sp.), Say, 1821 [M. canaliculata. Say) ; 'Telescopella, Gray, 

 1 837 (J/, undulata, Say = canaliculata, Say) ; Ceriphasia, Swain- 

 son, 1840 (C. sulcata. Swains, = M. canaliculata. Say); Anrjifrema, 

 Haldeman, 1841 (IT. armigera. Say); Elimia (sp.), H. & A. 

 Adams, 1854 {II. elevata. Say = canaliculata, Say) ; Alegara 

 {pars), H. & A. Adams, 1854 {31. lima, Conr. = P. verrucosa, 

 Raf.) ; Streptohasis, Lea, 1861 {S. Spillmanii, Lea = If. litceniata, 

 Conr.) ; Tryphanostoma, Lea, 1862 {II. canaliculata. Say) ; 

 Strepoma, ' Rafinesque MS.,' Haldeman, 1863 {Ceriphasia sulcata, 

 Swains. = II. canaliculata, Say, by substitution) ; Meseschiza, 

 Lea, 1864 (J/". Grosvenorii, Lea = II. armigera^ Say, deformed). 

 Type, Pleurocera verrucosa, Rafinesque.^ 



No type species has ever been cited for Pleurocera so far as the writer has 

 been able to determine. Tryon, Fischer, and Pilsbry appear to have 

 regarded Melania canaliculata. Say (not described till 1821), as typical, 

 but do not identify it with any of Eafinesque's species. Rafinesque first 

 described the genus in 1818 in the American Monthly Magazine and 

 Critical Rcvieio, and repeated the diagnosis in a somewhat altered fomi in 

 the Journal de Physique for 1819. Six species were named in the former 

 instance, but it does not appear that they ever passed the nomen nudum 

 stage. The generic description, with a little imagination, would tit any 

 member of this section of the family about equally well, so that nothing 

 can be gained from that. In the Annals of Nature, i, p. 11, 1820, 

 Eafinesque described Pleurocera verrucosa, and mentioned that the genus 

 had been diagnosed in the Journal de Physique. Tryon says in regard to 

 this species: "With no disposition to give place to the description of 

 Mr. Eafinesque, at the expense of naturalists of honesty and reputation, 

 I am still constrained, in this instance, to quote his name for the shell 

 that is so well known amongst us as Mr. Say's nupera. Indeed, I cannot 

 find any description of a species of shell, by Eafinesque, which indicates 

 so unmistakably the shell intended by him, as does the one here quoted. 

 It may. be mentioned, not as proof in itself, but merely as collateral 

 evidence of the correctness of my views of this species, that in a manuscript 

 by Eafinesque, entitled Conchologia Ohioensis, belonging to the Smithsonian 

 Institution, a rough pen sketch of Pleurocera verrucosa is given, which is 

 a very good representation of Mr. Say's nupera.'''' Pleurocera must there- 

 fore be dated from 1820, with P. verrucosa as the monotype. 



That Eafinesque's group was probably no more homogeneous than the 

 later divisions of the Adams and Lea, may be judged from the fact that in 

 1831 three more species were added, of which P. gonula, probably, and 

 P. quadrosa certainly are referable to canaliculata, while P. acuta is 

 doubtless Ambloxus virginicum. 



