156 



LAND AND FRESH- WATER SHELLS OF N. A. [I'ART T. 



rarely ever moves in a straight line, but is always turning and 

 whisking about, and this is done at times very quickly and ab- 

 ruptly. {Morse.) 



Fig. 267. 



Helix (?) Itarpa, Say. — Shell subperforate, ovately-conic, trans- 

 parent, very thin, with coarse, irregular lines of growth, pellucid, light 

 horn-color ; spire conical, rather obtuse ; whirls four, con- 

 vex, the upper ones smooth, the two last with prominent, 

 distant, tlxin, colorless fold-like ribs, slightly inclined back- 

 wards, the last whirl rounded, somewhat longer than the 

 spire ; columella subreceding ; aperture lunately oval ; peri- 

 stome simple, straight, its columellar termination briefly 

 reflected above. Greater diam. 2 mill. ; length 3^ ; aper- 

 ture 1| long, 1^- mill. wide. 



Helix harpa, 

 enlarged. 



Ilelix harpa, Say, Long's Exped. II, 256, pi. xv, f. 1 

 (1824) ; BiNNEY's ed, 29, pi. Ixxiv, f. 1. 

 Pupa costulata, Mighels, Proc. 13ost. Soc. Nat. Hist. I, 187 (1844). 

 Bulimus harpa, Pfeiffer, Zeitschr. f. Malak. 1847, 147 ; Mon. Hel. Viv. 



II, 150; in Chemnitz, ed. 2, no. 305, pi. Ix. f. 17-19.— Reeve, Con. 



Icon. no. 596 (1S49).— Binney, Terr. Moil. II, 290, pi. lii, f. 3.— W. 



G. BiNSEY, Terr. Moll. IV, 135. 

 Zoogenites harpa, Morse, Journ. Portl. Soc. I, 32, pi. i, f. 1-14 (1864) ; 



Amer. Nat. I, 608, f. 50, 51 (1S6S). 

 Helix amurensis, Gekstf., teste Morch. 



Gaspc ; Maine ; Xew Hampshire. Originally found by Say on 

 the Expedition to St. Peter's River, &c. British America, 

 English River, and James' Bay (Phil. Proc. 1861); 

 Sweden {Mai. Blult. 1867, p. 200); Norway, Lap- 

 land, &c. 



Jaw strongly arcuate, of uniform width through- 

 out, ends blunt ; anterior surface costate ; concave 

 margin indented, with a blunt median projection. 

 Lingual membrane with 20 rows of 17 — 1 — IT teeth ; centrals 



Fis:. 269. 



Fig. 268. 



Lingual dentition of Helix harpa. 



