FAMILY HELIC1D.E HELIX. 35 



the base on the inner edge. Pillar-lip with a short oblique tooth on the middle portion. 

 Umbilicus large and deep, exhibiting all the volutions. This is very indistinctly given in 

 the figure a. 



Color. Pale horn-color ; reflected portion of the lip and the tooth white. 



Diameter, 0-7-0-9. Height, 0-4-0-5. 



This species is somewhat allied to H. profunda, but is distinguished by its armed pillar- 

 lip ; in its delicate texture, it resembles multilineata. According to Mr. Wheatley, it is found 

 from Maine to Ohio. 



Helix monodon. 



PLATE III. FIG. 19. PLATE III. FIG. 21. a. b. 



Helix monodon. Racket, Tr. Lin. Soc. Lond. Vol. 13, p. 42, pi. 5, fig. 2. 



H. fraterna. Say, Long's Exped. St. Peter's, Vol. "2, p. 257, pi. 15, fig. 3. 



H. convexa. Lamarck, An. sans vert. Ed. Brux. Vol. 3, p. 408. 



H. fraterna. Adams, Am. Jour. Sc. Vol. 40, p. 272. 



H. monodon and fraterna. Binney, Jour. Nat. Hist. Vol. 3, pp. 360, 363, pi. 10, figs. 1/2. 



H. monodon. Gould, Invertebrata of Mass. p. 174, fig. 113. 



Description. Shell slightly convex, subdepressed, and covered with a hairy epidermis. 

 Whorls five or six, narrow, diminishing very gradually in width to the apex. Aperture 

 semilunar, restricted and closed by a deep groove behind the reflected portion of the outer 

 lip. The umbilicus either deep, but not exhibiting all the volutions as in fig. 21 ; or partially 

 or entirely closed by the reflected lip. The outer edge of the lip not projecting beyond the 

 surface of the whorl. Base rounded, much excavated in the umbilical region. Pillar-lip 

 with an oblique compressed elongated white tooth. 



Color. Epidermis dusky brownish or chesnut-colored ; reflected portion of the outer lip 

 occasionally with a pinkish hue. Animal yellowish brown, darker in front. 



Diameter, 03 -05. 



This species was originally described by Mr. Racket in the English Linnean Transactions, 

 with an open umbilicus. Mr. Say described the same under the name of fraterna, with a 

 closed umbilicus. Both are now believed to be identical. 



Found on rotten wood in forests, or in open fields under stones : a pair usually found to- 

 gether. It appears to extend through the Northern and Western States. It has been found 

 at Troy, and throughout the western district of this State. It seems to be allied to H. 

 hirsuta, but the tooth is much smaller than in that species, which is moreover imperforate. 



