344 PROCEEDINGS OF THE ACADEMY OF [1896. 



Ariolimax Columbianus fort7ia typicus Cockerell, Nautilus, V, p. 31 (1891). 



Arivliniax Columbianus forma maculatiis Ckll., Nautilus, V, p. 31. Binney, 

 Third Suppl. to Terr. Moll, V (Bull. Mus. Comp. Zool., XIX, No. 4), p. 211, 

 pi. vi, f. A. 



Ariolimax Columbianus forma ;/4'i^r Ckll., Nautilus, V, p. 32. 



Ariolimax subsp. Calijortticus foryjia maculatiis Ckll., Nautilus, V, p. 31 (foot 

 note). 



Ariolimary Columbianus var. stramineus Hemphill, Nautilus, IV, p. 130 

 (Feb., 1891). 



Geographic Distribution. — British Columbia (J. H. Keen) ; 

 Victoria (H. F. Wickham) ; Washington, at Taconia, and North 

 Bend, about 25 miles east of Seattle in the foot-hills of the Cascade 

 Mts. (P. B. Randolph) ; Nesqually (Case) ; Discovery Bay, Puget 

 Sound (Dyes) ; San Juan Island (Hemphill) ; California, at St. 

 Helena, Napa Co. (Hemphill) ; Santa Cruz Island (Hemphill, var. 

 stramineus). 



Color of alcoholic examples a lighter or darker shade of reddish- 

 brown, or sometimes ochraceous. Foot margin v/ithout dark vertical 

 lines (see descriptions of varieties). 



Melanistic form : Color of alcoholic specimens a slightly reddish- 

 brown, marked with large, irregular scattered black spots along the 

 sides, and with a rounded black spot on the mantle behind the middle. 

 In some specimens the spots on each side coalesce into a large, irreg- 

 ular black area. 



Anterior third of mantle free. 



Jaw (PI. XIV, fig. 10) with 13 to 17 ribs and riblets, which some- 

 times do not denticulate the basal margin ; but there is variation in 

 this respect. Teeth about as in A. Calijormcus (q. v.), but the outer 

 laterals have less lengthened cusps, and there are rather fewer bi- 

 cuspid outer marginals. The differences between the teeth of the 

 species are too slight to be of any practical diagnostic value. 



Shell oblong, convex above, calcified in the middle, but with a 

 broad, yellow, uncalcified peripheral portion. Nucleus median, near 

 the posterior end. Length 12, breadth 61, convexity 1? mm. 



The general internal structure (pi. XIII, fig. 1) and the digest- 

 ive tract (pi. XIII, fig. 2)* have been sufficiently described above. 



The genitalia (PI. XIV, fig. 7, typical form, and figs. 8, 9, black- 

 spotted form) present a rather long and stout penis, receiving the 

 vas deferens and a very short retractor muscle at its apex ; upon 

 opening the penis longitudinally (fig. 9) it is seen to contain a large 



* Compare Binney's figure of the digestive system in Proc. Acad. Nat. Sci.,. 

 Phila., 1874, pi. II, f. D, F. 



