Branson—The Fauna of the Residuary Auburn Chert. 45 
HORMOTOMA LATIANGULARIS, N. Sp. 
Pl. on. fo 13. 
Shell very small, four millimeters high, three milli- 
meters wide; apical angle fifty-seven degrees. Volutions 
five, increasing rapidly in size, lower volution forming 
considerably more than half of the shell. Band compara- 
tively broad, slightly convex, the convexity giving to the 
upper volutions a subangular appearance. Notch shal- 
low, slightly above the middle of the whorl. Lines of 
growth curved slightly backward on the upper side of 
_ the whorls. 
Hormotoma latiangularis can be readily distinguished 
from all other species of Hormotoma by its wide apical 
angle, low spire, and convex band. 
Species based on a single perfect specimen. Number 
11552 of the invertebrate paleontological collection of 
Walker Museum. 
HORMOTOMA FASCIATA, 0. Sp. 
Pl. vt. f. 16. 
Shell large, very loosely coiled, apical angle about six- 
teen degrees. Band narrow, convex, considerably ele- 
vated. Suture very deep, lines of growth coarse, bend- 
ing strongly backward from the suture to the band. 
Aperture slightly higher than wide. 
This species differs from H. gracilis in being more 
loosely coiled, having a very considerably raised band, 
_ the lines of growth bending backward more strongly, and 
the notch being deeper. 
This species is based on two specimens. Number 11509 
of the invertebrate paleontological collection of Walker 
Museum. 
PTEROTHECA EXPANSA. Himmons. 
Pl. ou. f. 14. 
Emmons, Natural History of New York, 4:397, 1842. 
A single specimen which is referred with some doubt to 
this species. It differs from the specimen figured by 
