90 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



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

 has given 20—1—20, 23—1—23, and 25—1—25. Of M. Duranti I have 

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

 Voyana had 24 — 1 — 24 teeth. M. sportella has 22—1—22. 



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

 be intermediate between Glandina and Zonites, differing from the fornu-r in 

 the presence of the transition teeth from true Literals 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 Fancouveren^s, Lea, Am. Phil. Trans., VI. 87, PI. XXIII. Fig. 72; Obs., 



II. 87 (1839). — Tkosciiel, Arch, fur Nat. 1839, II. 21. — DeKay, N. Y. 



Moll., 45 (1843). — Pfeiffer, Symbolte, 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 vcllicata, Fokbes, Proc. Zool. Soc. Lond. Mar. 1850, 75, PI. IX. Fig. 1. — 



Chemnitz, ed. 2, 11. 454, PI. CLIV. Figs. 42 - 44. — Reeve, Con. Icon., 



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

 Macrocyclis Vancouverensis, Tryon, Am. Journ. Coneh., II. 245 (1866). — 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.^ 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. 



1 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. 



