294 On Prophysaon, etc. 



than wide. A longitudinal line around the animal just 

 above the edge of foot. No distinct locomotive disk to 

 foot, but crowded, oblique furrows running from centre to 

 edge. Respiratory and anal orifices on the right margin of 

 mantle, slightly in advance of its centre, with the usual cleft 

 to the edge. Genital orifice behind and below, but quite 

 near to, the right eye-peduncle. No caudal mucus pore. 



Jaw slightly arcuate, ends blunt, but little attenuated. 

 Anterior surface with numerous (about fifteen in the only 

 known species) crowded, stout ribs, which denticulate either 

 margin (see pi. xiii, fig. 4). 



Lingual membrane (pi. xiii, fig. 7) as usual in the genus 

 Helix. Central teeth tricuspid. Laterals bicuspid. Mar- 

 ginals quadrate, irregularly cuspid, the inner cusps, as usual, 

 longest. 



Found in Oregon and California. Mr. Henry Hemphill 

 has collected specimens from Astoria to San Francisco Bay. 



This genus agrees with Limax by having an internal shell, 

 and by the position of the genital orifice. It difiers by its 

 ribbed jaw, by the subquadrate marginal teeth of the lingual 

 membrane, and by the anterior position of its respiratory 

 orifice. The genus is allied to Avion by its ribbed jaw, its 

 quadrate marginal teeth of the lingual membrane, and by 

 the anterior position of its respiratory oi'ifice ; it difiers in 

 having an internal shell, in the position of its generative ori- 

 fice and by the want of a caudal mucus pore. The genus is 

 also allied to Ariolimax in having a ribbed jaw, quadrate 

 marginal teeth to its lingual membrane and an internal 

 shell; it difiers in the position of both genital and respira- 

 tory orifices, and by the want of a caudal mucus' pore. The 

 absence of a distinct locomotive disk to the foot distin- 

 guishes our genus also from Avion, Limax and Ariolimax. 

 It is not readily confounded with any other known American 

 genus. The Irish genus Geomalacus is somewhat allied, 

 having an anterior respiratory orifice and an internal shell, 

 and being said by Gray to have crowded, quadrate teeth as 



