356 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



Helix Townsendiana, Lea, Trans. Am. Phil. Soc, VI. 99, PI. XXIII. Fij,'. 80 

 (1840) ; Obs., II. 99 (1839) ; in TuosciiEiAs An;h. f. Nat, 1839, II. 221. — 

 BiNNEY, Boat. Journ. Nat. Hist, III. 371, PI. XIII. ; Terr. Moll., II. 161, PI. 

 XIX. — DeKay, N. Y. Moll., 46 (1843). — Pfeiffer, Men. Hel. Viv., 1. 341 ; 

 in Chemnitz, ed. 2, I. 323, PI. LVII. Fi^s. 10, 11 (1846). — Reeve, Con. 

 Icon., 625 (1852). — Gould, U. S. Expl. Exp. Moll., &Q, Fig. 36 (1852).— 

 W. G. BiNNEY, Terr. Moll., IV. 15 ; L. & Fr.-W. Sh., I. 164 (1869). — Bland, 

 Ann. N. Y. Lye, VII. 362. 



Mesodon Townsendiana, TiiYON, Am. Journ. Conch., III. 46, PI. VIII. Fig. 8, 

 var. Fig. 6. 



Helix pedestris, Gould formerly. See Otia, 243. 



Helix rtiida, Gould formerly. 



Helix ptychophora, A. D. Brown, Journ. de Conch., 3d series, X. 392, Oct., 

 1876. 



A species of the Oregonian Region, traced thus far from Crescent City, Cali- 

 fornia, to the Straits of de Fuca ; it also passes the Cascade Mountains, into 

 the Interior Province, and along the mountains extends southeasterly into 

 Idaho and Montana.^ 



Animal corpulent, gradually tapering. Color pale yellowish-green ; surface 

 with rather sparse, feebly developed, elliptical granules, not seeming to have 

 anv regular arrantjement. Margin of disk rather broad, granulated, but regu- 

 larly marked with radiating furrows. 



A small variety (17 mill, diameter) is found, more strongly and coarsely 

 wrinkled, called //. ptychophora (see above). 



This is the most abundant species, especially along the coast, where, unlike 

 most of our American forest snails, it frequents open prairies among the fern. 

 It is particularly abundant on low sandy bars just above high tide, which are 

 covered with a deep, rich deposit of shell marl, and have been formerly favor- 

 ite camping-grounds of the Indians. These places, being very productive, are 

 much cultivated by the whites ; and immense numbers of this animal's shells 

 are found when the grass and bushes are first burnt off. They continue to live 

 in potato fields in the same places. The bare face of Cape Disappointment, 

 fronting the ocean, is also a locality. I did not find this species about Puget 

 Sound. (Dr. J. G. Cooper, P. R. R. Rep., p. 376.) 



Jaw as usual ; 9 ribs. 



The lingual membrane (PI. IX. Fig. Q) has 60—1—60 teeth. Another 

 membrane had 40 — 1 — 40 teeth. The variety ptychophora (PI. XV. Fig. N) 

 has similar dentition. 



It is peculiar in having decided side cutting points to central and lateral 

 teeth, and side cusps to the laterals. 



The genitalia are figured (PI. XIV. Fig. A). The accessory gland of the epi- 

 didymis is composed of several acini of different sizes. The genital bladder is 

 lengthened, oval, having a very short, stout duct. At the opening of the penis 



1 Recently found also iu Umatilla County, Oregon. 



