POLYGYRA. 153 



TRIODOPSIS (Vol. Ill, p. 143.) 



This section includes the American species which Tryon has 

 placed under " Isognomonostorna." The Old World forms, H. per- 

 sonata and subpersonata belong to the restricted genus Helix, near 

 CampylcBa, etc. The H. yucatanea Morel, (p. 146) belongs to the 

 H. texasiana group of section Dcedalochila. 



H. APPRESSA Say (p. 148). PI. 50, figs. 6, 7 (young.) 



This species attains a very large size in some parts of the South. 

 Specimens from AVoodville, Alabama, measure: alt. 10, diam. 21 mill. 



H. OBSTRICTA var. CAROLINENSIS Lea. PL 50, figs. 8, 9, 10. 



Shell distinctly angulated at the periphery, strongly costulate 

 above, smoother below ; the dull upper surface sometimes showing a 

 few sparsely scattered microscopic granules, under a lens. Aper- 

 ture having three strong teeth. Differs from typical obstricta in the 

 far less compressed peripheral keel ; from palliata in the very differ- 

 ent sculpture, etc. 



South Carolina. 



H. SARGENTIANA Johnson & Pilsbry. PI. 50, figs. 1-5. 



Shell depressed, imperforate, lens-shaped, carinated. Surface 

 strongly rib-striate, the striation disappearing toward the center of 

 the base ; under a lens the surface between the rib-like striae is seen 

 to be finely granulated. The aperture is wide, oblique; lip broadly 

 reflexed, flattened, the basal lip bearing a long lamella, as in H. 

 appressa. Upon the parietal wall there is a strong, high, curved 

 tooth, like that of H. elerata but longer. There are 6 whorls. The 

 color is light russet above, paler or whitish below. 



Alt. 11, diam. 24 mm. 



Alt. 12, diam. 24 mm. 



Alt. 9 diam. 22 mm. 



Woodville, Alabama. 



Helix sargenti J. & P., Nautilus vi, p. 8 (May, 1892). Not H. 

 sargenti BLD. H. sargentiana J. & P. t. c., p. 48. 



This species differs from H. appressa in its larger size, stronger 

 striation, and more especially in the granulated instead of spirally 

 striate microscopic sculpture, the strong carination, etc. It is allied 

 in shape and sculpture to H. carolinensis Lea, but differs in totally 

 lacking the upper lip tooth, in being flatter, more concave below, 

 etc. The young shells (pi. 50, figs 4, 5) differ markedly from 



