GASTEROPODA. 49 



Since, however, we have only gutta-percha casts of the exterior moulds, there 

 is no satisfactory means of separation. 



Formation and locality. In semicalcareous bands in the Upper Chemung, at 

 Nichols, Tioga county, N. Y. 



LOXONEMA LAXA, n. Sp. 

 PLATE XVIII, FIG. 12. 

 Loxonema terebra f Hall. Illustrations of Devonian Fossils : Gasteropoda, pi. 18. 1876. 



Shell thick, elongated, terebriform ; spire very rapidly ascending. Volutions 

 rounded, gradually expanded to the last one which is ventricose; col- 

 umellar lip greatly extended, making the lower part of the aperture very 

 acute ; about four and a half volutions in the length of two inches and 

 three-fourths from the base — the entire shell having had about one or 

 two more. 



Surface marked by coarse, obtuse, elevated striae, which are obsolete on the 

 upper part of the volution, and make a very gentle curve over the 

 periphery. 



. The specimens examined are essentially casts of the interior, sometimes 

 preserving portions of the shell which is crystalline and adhering to the 

 matrix. Slight indications of the surface markings are sometimes preserved 

 on the cast; and in one individual may be seen the strong elevated striae 

 characteristic of the genus. The species has been abundant in the locality 

 where it occurs, since, in a single specimen of the rock therefrom, of the size 

 of two by three inches, and scarcely more than an inch thick, fragments of as 

 many as eight or nine individuals are to be seen. It is associated with numer- 

 ous specimens of Bellerophon, Pleurotomaria and Platyostoma ; and the Mac- 

 rocheilus (Holopea) macrostomus, known elsewhere only in the Hamilton group, 

 occurs in the same position. 



Formation and locality. In the higher beds of the Chemung group, at Nichols, 

 TlOga county, N. Y. 

 7 



