Genera of Terrestrial MoUusca, etc. 203 



many species of North American Succinea, we think erro- 

 neously, to Brachyspira. In Land and Fresh Water Shells 

 of JVorth America (1869) we adopted the latter in the sense 

 in which it is used by Albers (ed. 2). 



Omalonyx D'Orb. 



Albers (I. c, 311) refers to 0. unguis F6r. as the type of 

 this group. D'Orbigny (Voy., 229, t. 22, figs. 1-7) gives 

 the following description of the animal : 



" Allonge, ovale, d^prirae, beaucoup trop grand pour rentrer dans la 

 coquille, occupant pres de trois fois la surface de celle-cl; pied tres large 

 debordant de toutes parts, aiTondi en avant, acumine posterieureraent, lisse 

 en dcssous et endessus; mauteau formant un bourrelet autour de la 

 coquille, qu'il recouvresur les bords, etroiten arriere, plus large et comme 

 plisse en avant ; col assez long ; tete etroite ; tentaQules courts ; orifice 

 des poumous sous le bord droit du manteau, vers sa partie moyenne." 



Fischer (Melang. Conch., p. 67, pi. vi, f.l) describes the 

 animal of 0. unguis and its dentition. 



Sometime since we were indebted to Mr. John G. Anthony 

 for specimens collected by him (Agassiz' expedition) in 

 Brazil, and found, on examination of the jaw and lingual 

 dentition, that both agree with the figures given by Heyue- 

 mann (Mai. Blatt., 1868, taf. iv, fig. 5) of the jaw and teeth 

 of Pellicula convexa Martens, of which figures we add copies 

 (plate ix, figs. 12-14). 



As already mentioned, we have lately received from Gov- 

 ernor Rawson specimens in alcohol of animal and shell of 

 O. unguis, collected in Guadeloupe by Schramm, and find 

 that both jaw and teeth are precisely similar to those of the 

 Brazilian examples. 



It appears, irrespective of form of animal and shell, that 

 should even Amphibulima prove like Omalonyx to be elas- 

 mognathous, the lingual dentition of the latter does not 

 warrant its being treated, as proposed by Guppy, as a section 

 of the former genus. 



Guppy has lately discovered- in Trinidad, but not yet, we 



