1898.] NATURAL SCIENCES OF PHILADELPHIA. 235 



to the entrance of the epiphallus (fig. 42). The latter is longer than 

 in H. glandulosa, and the retractor muscle is inserted at its root. 

 Spermatheca small, its duct very stout, inserted upon the atrium. 



Shell slightly convex, long-oval, with clear yellow cuticle, thin 

 calcareous layer, and posterior nucleus; the surface lightly marked 

 with growth lines. Length 8, width 5 mm. 



Jaw low, wide, with about 14 low, broad ribs separated by nar- 

 row intervals. Radula : Marginals with rather long inner cusps 

 (PI. XVI, fig. 85). 



Old Mission, Idaho (Henry Hemphill). 



This species has a proportionally smaller shell than H. glandulosa, 

 a longer, less compressed and less carinated tail, with no trace of a 

 caudal horn and no perceptible caudal gland ; the mantle is not 

 papillose, the pedal furrows rise abruptly at the tail, uniting over 

 it, and the genitalia differ in important respects, as noticed under 

 the description of H. glandulosa. 



Genus ARIOLIMAX Morch, 1860. 



Ariolimax Morch, Malak. Blatter, VI, p. 110. Pilsbry & Vanatta, Proc 

 Acad. N. S. Phila., 1896, p. 342. 



To the generic characters described and implied in our former 

 paper, the following may be added : 



Tail gland (PI. XV, fig. 81) a peculiar triangular mass of tissue, in 

 alcoholic specimens deeply fissured transversely. 



Muscle system (PI. XIV, fig. QQ, A. columbianus) having the 

 buccal and eye retractors converging posteriorly, their proximal in- 

 sertions contiguous at the posterior edge of the diaphragm. Buc- 

 cal retractor very deeply bifurcate. An accessory muscle, the 

 " retensor," arises with the retractor group, to the left of the median 

 line, and passing forward is inserted in the integument of the neck, 

 on the right side or above. 



Lung (PI. XV, fig. 73, A. columbianus, the kidney removed) and 

 kidney (PI. XV, fig. 74, A. columbianus) as usual in Arionidce. 

 Auricle concealed by kidney, ventricle (fig. 73, 74, v) exposed. 



Subsequent studies support the conclusion reached in our former 

 paper, that Ariolimax is more closely allied to Aphallarion than to 

 any other known genus. 



Genus APHALLARION Pilsbry & Vanatta, 1896. 

 Aphallarion P. & V., Proc Acad. N. S. Phila., 1896, p. 348. 

 Tail pore as in Ariolimax. 



Muscle system (PI. XIV, fig. 67) substantially like Ariolimax in 

 arrangement of the buccal and eye retractors, except that the right 



