MUSEUM OF COMPARATIVE ZOOLOGY. 213 



showing the volutions clearly. Greater diameter, 9 mm. ; lesser, 7 mm. ; 

 height, 2£ mm. 



Helix (Triodopsis) Ropen, Pilsbry. The Nautilus, Vol. III. No. 2, June, 1889, 

 p. 14. 



Bedding, Shasta Co., California, in drift of the Sacramento River, three 

 dead shells were collected by Mr. Edward W. Roper, of Chelsea, Mass. 



The above description is drawn from one of the original specimens, kindly 

 lent me by Mr. Roper, while another in the collection of the Academy of Natu- 

 ral Sciences of Philadelphia, from which Mr. Pilsbry drew his description, is 

 figured above. The third specimen was given by Mr. Roper to Mr. Henry E. 

 Dore of Portland, Oregon. 



Never having seen a specimen of P. Harfordiana, I cannot say if this species 

 is identical with it. At least, it must be nearly allied. 



Aglaja fldelis, Gray. 



New figures of several forms of this species are given. Plate X. Fig. A 

 represents the black elevated form approaching infumata. Its sculpturing is 

 given in Fig. B. The small, black, elevated form is given in Fig. C, with its 

 sculpturing in D ; the small, depressed form, in E. 



Aglaja infumata, Gould. 

 Plate X. Fig. F, gives an enlarged view of the hirsute surface. 



Arionta arrosa, Gould. 



Plate XL Fig. A gives this species. A form of arrosa nearly approaching 

 A. exarata is given in Fig. B, its sculpturing in Fig. C. 



Arionta exarata, Pfeiffer. 

 The typical form and its sculpturing are given on Plate XI. Figs. D and E. 



Arionta Mormonum, Pfeiffer. 



The typical form is given on Plate XI. Fig. F. The rrpr 

 variety (Vol. V. p. 141) approaching Aglaja Hillebrandi, 

 is given in Figs. G and H ; the sculpturing of the same 

 form, on Plate X. Fig. G. The genitalia of this form 

 are the same as of the type. 



Arionta sequoicola, J- G. Cooper. 



A figure of the sculpturing of this species is here ~" EnlarBed sculptnri ng of 

 given, greatly enlarged. Arionta sequoicola. 



