92 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



MacrocycUs sportella, Tuyon, Am. Journ. Conch., II. 245 (1866). — W. G. BiN- 

 NKY, L. k Fr.-W. Sh., I. 57 (1869). 



From San Diego to Puget Sound ; confined to the Pacific Province. 



See remarks under M. Vancouverensis. 



In extreme forms of this species the revolving lines mark the whole surface, 

 even in the umbilicus and in the interstices between the incremental striae. 



Jaw and lingual membrane as usual in the genus, the latter resembling that 

 of M. Vancouverensis. Teeth 22—1—22. PI. XV. Fig. K. 



MacrocycUs concava, Say. 



Vol. III. PI. XXI. 



Shell depressed, very slightly convex on the upper surface ; epidermis whit- 

 ish horn-color, sometimes with a tinge of green ; whorls 5, above flattened, 

 below rounded, finely striate obliquely, and sometimes with microscopic revolv- 

 ing lines ; the outer whorl spreading a little towards the aperture ; suture rather 

 deeply impressed ; umbilicus wide, deep, exhibiting all the volutions to the 

 apex ; aperture rounded, somewhat flattened above, its edge frequently tinged 

 with reddish-brown ; peristome sub-reflected at its columellar extremity, 

 simple above, and in some specimens considerably depressed near its junction 

 with the outer whorl ; columella with a thin callus, the edge of which connects 

 the upper and lower extremities of the peristome. Greater diameter 21, lesser 

 16 mill. ; height, 7 mill. 



Helix concava, Say, Journ. Acad., II. 159 (1821); Binney's ed., 20. — Binney, 



Bost. Journ. Nat. Hist., III. 372 (1840), excl. pi. ; Terr. Moll., II. 163, PI. 



XXI. — Adams, Vermont MoUusca, 159 (1842), excl. syn. Vancouverensis. — 



DeKay, N. Y. Moll., 33, PI. II. Fig. 15 (1843). — Pfeiffer, Mon. Hel. Viv., 



IV. 159. —W. G. Binney, Terr. Moll., IV. 63. — Leidy, T. M. U. S., I. 



258, PI. XII. Figs. 9-11 (1851), anat. — Mouse, Amer. Nat., I. 412, Figs. 26, 



27 (1867). 

 Helix planorboides, F^russac, Hist. Nat. des Moll., Tab. LXXXII. Fig. 4. — 



Pfeiffer, Mon. Hel. Viv., I. 200; Symbolae, II. 37. —Chemnitz, ed. 2, II. 



164, PI. XCV. Figs. 17-19 ; PI. CLIV. Fig. 45 (1851). — Reeve, Con. Icon., 



674 (1852). — Deshayes in F6r. I. 87. 

 Helix dissidens, Deshayes in F^r. Hist, I. 97, PI. LXXXIV, Figs. 1, 2. 

 MacrocycUs concava, Morse, Journ. Portl. Soc, I. 12, PI. V. Fig. (1864). — 



Tryon, Am. Journ. Conch., II. 245 (1866). —W. G. Binney, L. & Fr.-W. 



Sh., I. 56 (1869). —Gould and Binney, Inv. of Mass., ed. 2. p. 406 (1870). 



A Post-pleiocene species still existing in full vigor in the Eastern Province. 

 Ranges from Canada to Georgia, from Michigan to Missouri. The finest 

 specimens occur in the southern part of the Appalachian chain. 



Animal : upper surface grayish, tentacles and eye-peduncles bluish, base 

 dirty-white, collar reddish-orange, posterior extremity slightly tinged with the 



