300 On Prophysaon, etc. 



jaw and lingual dentition. These were also given in our 

 Land and Fresh Water Shells N. A., I, p. 278, figs. 496-8 

 (1869). As late as 1868 the species is still retained in 

 Limax b^^Tryon (Amer. Journ. Conch. Ill, 315), who gives 

 a copy of one of Gould's figures from the Terrestrial 

 Mollusks. 



The genus has affinities with, but is readily distinguished 

 from, Limax, Avion and PropJiysaon. It agrees Avith 

 Limax in having an internal shelly plate, in the position of 

 its respiratory orifice and its distinct locomotive disk ; but it 

 diSers in having a caudal mucus pore, a ribbed jaw, quadrate 

 (not aculeate) marginal teeth on the lingual membrane, and 

 in the position of its genital orifice. With Avion it agrees 

 in having a mucus pore, a distinct locomotive disk, a ribbed 

 jaw, in its lingual membrane, and position of the genital 

 orifice ; but it differs in the position of its respiratory orifice 

 and its internal shell. With Pvophysaon it agrees in having 

 an internal shell, a ribbed jaw, in its lingual membrane ; but 

 clitfers in the position of the genital and respiratory orifices, 

 in its distinct locomotive disk and caudal mucus pore. 



From the other sluglike, or semi-sluglike American genera, 

 Tehennophovus, Pallifeva, Binueia, HempJiillia, Vevonicella, 

 it is most readilv distinguished. 



Several species are known : — 



AvioUmax Colambianus, Gould (Limax) see L. and F. W. 

 Shells, I, 279, for its synonymy, to which must be added 

 Limax Columbiamis, Tryon, Amer. Journ. Conch., Ill, 

 315, pi. xvi, fig. 1, copy. (1868.) This is found in 

 Washington Territory and Oregon, confined, according 

 to Dr. Cooper, to the west of the Cascades. 



AvioUmax Califovnicus, J. G. Cooper, Proc. Phila. Acad. 

 Nat. Sci., 1872, p. 146, pi. iii", fig. D, 1-3. California, 

 in the Coast Range, once only in the Sierra Nevada in 

 lat. 39°. 



