2t8 



LAND ANP FRESH-WATER SHELLS OF N. A. [PART I. 



The position of the orifice of respiration on the anterior portion 

 of the shield, and the presence of the mucus pore at once indi- 

 cate the generic position of this species. I have had no oppor- 

 tunity of examining the jaw or the rudimentary granules. 



It is readily distinguished by the leaf-like areolae which mark 

 the surface, and suggest the specific name. 



Spurious Species of Arion. 



Arion (Lorlien) emplricortim is quoted without anthoritj or description 

 from tlie Western States by Gkateloup (Distr. Geogr. de la Familla 

 des Limaciens). 



ARIOLimAX, MoRCH. 



Body attenuated towards the posterior extremity, which is 

 carinated strongly. Surface with oblong tuberosities. Mantle 

 anterior, bluntly trnncated before and behind, minutely granu- 

 lated, free at the front and sides, attached posteriorly, containing 



Fig. 496. 



Ariolimax columbianus, one-half natural size. 



a testaceous rudiment. Longitudinal furrows along the sides 

 above the foot. Locomotive disk — ? Respiratory orifice at 

 the posterior third of the shell. Anal orifice — ? Orifice of the 

 generative organs — ? A caudal mucus pore. 



Testaceous rudiment hexagonal, longer than wide, ends 

 pointed acutely, not spiral. 

 F'S- -1^7. Jaw arcuate, with numerous crowded 



anterior ribs, danticulating the concave 

 margin. 



Lingual membrane (of A. cohtmhiamif^) 

 very broad and long, composed of about 

 120 rows of teeth, each row containing 113 teeth (56 — 1 — 56); 



Jaw of 

 Ariolimax columbianus. 



