ARIOLIMAX. 231 



The extreme length of the digestive system is three times that of the whole 

 body of the animal, at least in its contracted state. 



The jaw in all the forms of Ariolimax is quite thick, dark horn-colored, 

 arcuate; ends but little attenuated, blunt; anterior surface with stout ribs, 

 denticulating either margin. I have figured (1. c.) the jaw of A. Colum- 

 bianus, which has about 12 ribs (on p. 227 another specimen with 18). In 

 A. Californicus, from Mr. Anthony, there were 13 ribs to the jaw; 14 in Mr. 

 Hemphill's specimen of the same. In A. niger Dr. Cooper describes about 

 20, but in one specimen I found but 8. In A. Hemphilli, I found 8-12 ribs; 

 in A. Andersoni, 13 ribs. 



The pouch of the lingual membrane is shown in PL II. Fig. D, 5 (1. c.) The 

 membrane is as usual in the HeUc'idce, with tricuspid central, bicuspid lateral, 

 and quadrate marginal teeth, showing simply a modification of the laterals. In 

 Land and Fresh- Water Shells, I. p. 280, I have figured the lingual membrane 

 of the true northern A, Columbianus, which has the general arrangement of 

 Patula. See also PI. V. Fig. E. The marginal teeth are shown to have one long 

 denticle and a small, subobsolete side denticle. This form of marginal teeth 

 I have found also in one of Dr. Cooper's types of A. niger (PL V. Fig. D), and 

 in A. Californicus (PL V. Fig. F), also in A. Andersoni? (Fig. G) and A. Hem- 

 philli (Fig. H). This form of marginal tooth may therefore be considered char- 

 acteristic of the genus, though in one specimen, supposed to be A. niger, I no- 

 ticed marginal teeth with the outer cusp much more developed and bifid, and 

 figure them in Fig. D, /, of PL V. The gradual change from the first lateral 

 tooth to the last marginal tooth is well shown in Fig. H of PL V., which repre- 

 sents the teeth of A. Hemphilli. 



There is no retractor muscle to the buccal mass in A. Californicus and A. 

 Columbianus, but a very stout, broad one to the whole head, attached to the 

 outer integument below the buccal mass, and running along some distance on 

 the floor of the general visceral cavity, to which finally it becomes attached. 



Ariolimax Columbianus, GOULD. 

 Vol. III. PL LXVI. Fig. 1. 



Color a dark, dirty, greenish-yellow, either uniform or in some varieties 

 clouded with large purplish-black, irregular blotches. The body is large and 

 corpulent, the anterior portion elevated, with the back rounded, and the pos- 

 terior portion strongly carinated ; at the posterior tip there is a mucus pore. 

 The margin of the foot extends beyond the mantle and forms a ruffle around 

 the animal, with transversely oblique markings. The surface is tessellated with 

 coarse elongated papillae arranged longitudinally. The mantle is broad, truncated 

 in front, minutely granulated, with the respiratory orifice at the posterior third. 

 Face vertically wrinkled ; eye-peduncles rather short, thickened at base, colored 

 like the body and finely granulated ; tentacles long and slender. Length, 5 

 inches. 



