90 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



branes examined by me gave 24 1 24, one other 18 1 18. M. concava 

 has given 20120, 23123, and 25125. Of M. Duranti I have 

 counted but one membrane having 18 1 18. A single membrane of M. 

 Voyana had 24124 teeth. M. sportella has 22122. 



To sum up the characters of the dentition of Macrocyclis, it may be said to 

 be intermediate between Glandina and Zonites, differing from the former in 

 the presence of the transition teeth from true laterals to true marginals, differ- 

 ing, however, from the latter by the absence of true lateral teeth. 



Macrocyclis Vancouverensis, LEA. 

 Vol. III. PI. XX. 



Shell widely umbilicated, depressed, very slightly convex on the upper 

 surface ; epidermis light greenish-yellow ; whorls 5, nearly flat above, pro- 

 tuberant and rounded on the lower surface, lines of growth very minute, with 

 crowded, microscopic revolving striae, the outer whorl expanding a little towards 

 the aperture ; umbilicus wide and deep ; aperture transverse, somewhat rounded, 

 flattened above by a depression of the peristome near its junction with the 

 body-whorl, its edge tinged with rufous ; peristome thin, acute, slightly reflected 

 at the base of the shell, simple above, the two extremities approaching each 

 other, and connected by a thin callus, which covers the columella. Greater 

 diameter 31, lesser 26 mill. ; height, 14 mill. 



Helix concava, BINNEY, Bost. Journ. Nat. Hist., III. 372, PI. XIV. (1840), not 



of SAY. 



Helix Vancouverensis, LEA, Am. Phil. Trans., VI. 87, PI. XXIII. Fig. 72; Obs., 

 II. 87 (1839). TROSCHEL, Arch, fur Nat. 1839, II. 21. DEKAY, N. Y. 

 Moll., 45 (1843). PFEIFFER, Symbolse, II. 41 ; Mon. Hel. Viv., I. 200; in 

 CHEMNITZ, ed. 2, II. 146, PI. XCIV. Figs. 21 -23. BINNEY, Terr. Moll., 

 II. 166, PI. XX. W. G. BINNEY, Terr. Moll., IV. 19. GOULD, U. S. Expl. 

 Ex., 36, Fig. 37 (1852). REEVE, Con. Icon., No. 669 (1852). 

 Helix vellicata, FORBES, Proc. Zool. Soc. Lond. Mar. 1850, 75, PI. IX. Fig. 1. - 

 CHEMNITZ, ed. 2, II. 454, PI. CLIV. Figs. 42 - 44. KEEVE, Con. Icon., 

 No. 673 (1852). PFEIFFER, Mon. Hel. Viv., III. 155. 



Macrocyclis Vancouverensis, TRYON, Am. Journ. Conch., II. 245 (1S66). W. G. 

 BINNEY, L. & Fr.-W. Sh., I. 54 (1869). 



A species of the Pacific Province ranging from lat. 60, in Alaska, to lat. 

 37 ; above lat. 49 it passes the Cascade Mountains, and ranges southeasterly 

 into Idaho and Montana. 1 In these latter localities the species is reduced in 

 size. It reaches its greatest development in the region of Astoria. 



Animal short posteriorly, sub-cylindrical, very light-colored, giving a straw- 

 colored reflection, sides pearly, marked with longitudinal lines of coarse, elon- 

 gated, squamose granules, about eight or ten on each side. 



l A most interesting paper on the distribution of the West Coast species, by Dr. 

 J. G. Cooper, will be found in Vol. IV. of Amer. Journ. of Conch. 



