236 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



The jaw is as usual in the genu?, wide, low, with about thirteen broad, sep- 

 arated ribs, denticulating either margin. The lingual membrane is as usual. 

 Teeth, 48 — 1 — 48, The characters of the teeth are sufficiently shown in my 

 Fig. G, of PI. V. The change from laterals to marginals is very gradual, the 

 latter being but a simple modification of the former. 



The genitalia (PI. XII. Fig. E) are very much like those of A. niger, espe- 

 cially in the shape of the penis sac, and the peculiar accessory organ (p, g) } 

 probably a vaginal prostate. The genital bladder differs some- 

 Fig. 136. what in shape, and also the testicle. 



The rudimentary shell has decided concentric layers. The 

 caudal mucus pore is as in A. Columbianus. 



Ariolimax Andersoni ? see W. G. Binney, Ann. Lyo. Nat. Hist, 

 of N. Y., XI. 182, PL XII. Fig. 9 (1875). 



Should this not prove the species described as Arion Andersoni 

 by Dr. J. G. Cooper, it must receive a new name. It is a true Ariolimax, 

 most nearly related to A. niger. The latter species wants the foliated reticu- 

 lations, and has its posterior termination more blunt, with a decided lateral 

 cleft at the mucus pore. 



PROPHYSAON. 1 



Animal limaciform, attenuated behind. Mantle anterior, small, obtuse be- 

 fore and behind, its margins free as far back as the cleft for the respiratory 



Fig. 137. 



Prophysaon Hemphilli. 



orifice, enclosing a simple, not spiral, subhexagonal shell, which is longer than 

 wide. A longitudinal line around the animal just above the edge of foot, No 



l Animal limaeiforme, postice acuminatum. Pallium antice positum, parvum, obtusum, 

 marginibus anterioribus liberis, testam simplicem, haud spiralem includens. Margo in- 

 fer* aninialis sulco longitudinali supra pedem posito instructs. Discus distinctus gres- 

 sorius nullus, Apertura respiratoria et analis ad inarginem dextrani pallii paululum 

 anteriorem positae. Apertura genitalis ad latus dextrum, pone et infra tentaculum 

 ocujigerum. Porus mucosus caudalis nullus. , 



Testa interna longa, subhexagonalis. 



Maxilla leviter arcuata, costis numerosls validis (in specie unica circa XV), confertis 

 mijnita ; marginibus dantioulatis. 



Lamina lingiulis ut in Helice ccnstituta. Dentes medians tricuspidatse, laterales bi- 

 cuapidataa, marginales quadratae, irregulariter cuspidat®. 



Habitat in Oregon et in California. Specimina plurima collegit H, Hemphill de Astoria 

 u»que ad San Francisco. 



