332 NEW YORK STATE MUSEUM 



Dimensions. This shell rarely exceeds 5 mm in diameter at full growth. 



Habitat. Genesee province ; Naples subprovince. A rare species 



observed only as barite replacements in the concretions from Honeoye lake, 



Livingston co. N. Y. 



loxonema Phillips. 1 84 1 



Loxonema noe Clarke 



Plate 18, fig. 6-10 



Loxonema noe Clarke, U. S. Geol. Sur. Bui. 16. 1885. p. 55, pi. 3, fig. 10 

 Shell of small size and delicate proportions, terete and slender. 

 Whorls at full growth 13 ; slightly but regularly convex, becoming more 

 depressed toward the aperture. The incipient shell lies in position normal 

 to the rest of the whorls, and the surface of the first two whorls, which con- 

 stitute the nepionic shell growth, is smooth. When vertical or concentric 

 ridges begin to. appear, they, are sharp, almost angular and are at first nearly 

 uprignt, but on the fourth and fifth whorls begin to show a decided 

 obliquity. After the ninth whorl they manifest a retral curve near the 

 suture, and the course of the ridges becomes broadly sigmoidal. These 

 ridges number, quite uniformly, about 18 for early and late whorls alike, but 

 on the final volutions their regularity is-modified by the interspersion between 

 them of finer ridges or the irregular growth of the larger ones, all becoming 

 relatively less conspicuous features of the surface. Finer vertical striae 

 covering these ridges and the intervening furrows are visible over the later 

 whorls. The suture is short and simple, both whorl surfaces rising there- 

 from with equal convexity. Aperture subcircular or vertically somewhat 

 elongate ; outer lip thin, inner lip not calloused. Columella gently twisted, 

 projacent. Base nonumbilicate. 



Dimensions. A fully grown shell has a hight of 1 7 mm, a width at 

 the base of 4 mm. These are the normal adult measurements. 



Observations. This species is at once distinguishable from the forms 

 common in the Hamilton fauna beneath (L. delphicola, L. hamil- 

 t o n i ae) by its uniformly small size, more delicate and slender form and less 

 variable surface characters. It is however freely a descendant of such species. 



