506 PALAEONTOLOGY OF ILLINOIS. 



Genus STKEPTACIS. 



STREPTACIS WHITFIELDI, Meek. 



PI. 29, Fig. 1. 

 Streptacis Whitfieldi, MEEK. Proceed. Acad. Nat. Sci., PLila., 1871, p. 173. 



Position and locality Roof of Danville coal; Danville, Illinois. 



Genus LOXOKEMA. 



LOXONEMA SEMICOSTATA, Meek. 



PI. 29, Fig. 2. 



Loxonema semicostata, MEEK, 1871. Proceed. Acad. ]S"at. Sci., PLila., p. 174. 



Chemnilzia attemiata, SIKVEKB, 1858. Am. Jour. Sci., Vol. 25, n. s., p. 259. (Xot Loxtnema attenuata, 

 Hall, 1859.) 



Position and locality Eoof of Danville coal 5 Danville, Illinois. 



Genus ACLIS, Loven. 



ACLIS ROBUSTA, Stevens. 



PI. 29, Fig. 6. 

 Aclis robusta, STEVENB, 1858. Am. Joiir. Sci, Vol. 25, n. s, p. 259. 



Position and locality Koof of Danville coal 5 Danville, Illinois. 

 Genus POLYPHEMOPSIS, Portlock. 



POLYPHEMOPSIS CHKYSALLIS, M. and W. 



PI. 28, Fig. 7. 

 Polyphemopsis chrysallis, MEEK and WOHTHEN, 1866. Proceed. Acafc ISTat. Sci., PLila., p. 267. 



SHELL small, subfusiform ; spire conical, moderately ele- 

 vated, pointed at the apex; yolutions nine, a little convex, 

 and increasing gradually in size, last one forming about 

 two-thirds the entire length, and rather produced below; 

 suture distinct, aperture narrow-suboval, acutely angular 

 above, and narrowly effuse below; inner lip apparently 



