HELIX. 417 



a third one but slightly raised between these two. At the base of 

 the shell and far within the aperture are two more revolving ribs, 

 running about a third of one volution. These are plainly visible 

 through the substance of the shell. A heavv coluniellar tooth or 

 rib extends from a slight distance within the aperture, nearly one 

 volution back. This columellar tooth thickens the sul)stance of the 

 shell in the umbilical region and causes a distinct fold without the 

 shell. A most singular feature is revealed in the structure of the 

 parietal lamiufe. With an ordinary magnifying power small swell- 

 ings are seen at close intervals along these laminte, which when 

 magnified four hundred diameters are seen to be surmounted with 

 from five to ten sharp spines pointing toward the aperture ; these 

 swellings appear to coincide in number and position with the raised 

 ribs without the shell, though they are not formed at the same 

 time ; for as these laminae approach the aperture they become at- 

 tenuated and disappear. The surface upon which these laminge 

 rest is granulated, and not smooth as is generally the case with the 

 interior of shells. It is difficult to imagine the use of these spiny 

 projections, unless they may act in some way as points of resistance 

 to the animal for the support of a very heavy shell. 



Helix hirsuta. 



Fig. 116. 



Shell globular, hairy, chestnut colored ; aperture very narrow ; outer lip re- 

 flexed, having a fissure on its inner margin ; pillar lip with a long compressed 

 tooth; umbilicus closed. 



Helix hirsuta, Sav, Journ. Phila. Acad. i. 17 (1817) ; ii. 161 ; ed. Binney, 8. — Binnet, 

 Bost. Journ. Nat. Hist. iii. 365, pi. 10, fig 3 (1840) ; Terr. Moll. ii. 150, pi. 42, fig. 

 3, e.\cl. stenotrrma. — 'DE K.A.Y, N. Y. Moll. 36, pi. 3, fig. 27. — Gould, Inv. 175, 

 fig. 116 (1841). — Feruss.ac, Tab. Syst. 38; Hist. pi. SOrr, fig. 1. — Deshayes, in 

 Lamauck, viii. 113; 3d ed. iii. 308; Encyc. Meth. ii. 253 (1830) ; in Fer. i. 140. — 

 Mrs. Gray, Fig. of Moll. An. pi. 193, fijj 8, ex Bo^^t. Journ. — Pfeiffer, Mon. 

 Hel. Viv. excl. var. ,■? i. 421 ; in Chemnitz, 2d ed. cxcl. var. i. 374 (1846) ; pi. 65, 

 figs. 9-11 (1849). — Reeve, Con. Icon. No. 714 (1852). — Leidy, Terr. Moll. U. 

 S. i. 257, pi. 11, figs. 5, 6 (1851), anat. — W. G. Binxey, Terr. Moll. iv. 62. — 

 Bland, Ann. Lye. N. Y. vii. 327. — Morse, Am. Nat. i. 151, figs. 14, 15 (1867). 



H'iix simiata, G.melix (teste Pfeiffer). 



Helix isojnomnstoma, Gmelix (teste Pfeiffer). 



Tridopsis Idrsiita, Woodward, Man. pi. 12, ficj. 7, no descr. 



Helix frcUerna, Wood, Index, Suppl. 21, viii. fig. 16 (1828) ; ed. Hanley, 226, fig. 16. 



Helix porcina, Say, Long's Exped. (1824) ii. 257, pi. 15, fi^. 2 (young) ; Binney's cd. 

 30, pi. 74, fig. 2. — De Kay, N. Y. Moll. 45 (1843). — Pfeiffer, Mon. Hel. Viv. iii. 

 97. — Bland, Ann. Lye. N. Y. vi. 344, with figure (1858). 

 27 



