572 GEOLOGY OF THE YELLOWSTONE NATIONAL PARK. 



had in hand the same form with which I am dealing, but his descriptive 

 remarks are too general to render the species identifiable. 



Formation and locality: Madison limestone, Crowfoot Ridge, Gallatin 

 Range, bed 24; A. C. Gill. Kinderhook age, Burlington, Iowa. 



NATICOPSIS McCoy, 1844. 

 Naticopsis (!) sp. 



PI. LXVI, fig. 13a. 



There is only one specimen of this gastropod, an internal cast in a 

 siliceous matrix. The peritreme is incomplete and there is iio telling to 

 what extent the lower whorls are broken away. Specific identification is 

 therefore out of the question. It appears to belong to the genus Naticopsis. 



Formation and locality: Madison limestone, Crowfoot Ridge, Gallatin 

 Range, top of bed 24; J. P. Iddings. 



LOXONEMA Phillips, 1841. 



LOXONEMA (?) sp. 

 PI. LXVI, fig. 9a. 



This species consists of the cast of a rather large elongate gastropod 

 shell, probably belonging to the genus Loxonema. The specimen consists 

 of four whorls and part of a fifth, and is very gradually tapering. It some- 

 what resembles L. tennilineaium Swallow, of the Chouteau limestone, but 

 the sides converge less rapidly and the peripheral outline of each whorl is 

 much flattened. The shell must have been very thin, for the convolutions 

 are now almost in contact. 



Length of the imperfect specimen, 27 mm.; width at the base, 12.5 mm.; 

 width at the top, 7.5 mm. 



Formation and locality: Madison limestone, Crowfoot Ridge, Gallatin 

 Range, top of bed 26; J. P. Iddings and W. H. Weed. 



