ORTHOCERATIDJE. 
15 
Orthoceras Halli ?, 8. A. Miller. 
1875. Orthoceras Halli, S. A. Miller, Cincinnati Quart. Jonrn. Sci. 
vol. ii. No. 2, p. 128, f. 14. 
Sp. Char. Section elliptical, rate of increase about 1 in 13. Septa 
numerous, about 3 lines apart. Sipbnncle eccentric, somewhat 
inflated between the chambers. “ Body-chamber about ^ the length 
of the shell.” {Miller.) Surface of the test unknown. 
Horizon. Cincinnati Group ( = Lower and Middle Bala?). 
Localities. Cincinnati, Ohio ; Danville, Kentucky. 
Fairly well represented. 
Orthoceras Dyeri ?, S. A. Miller. 
1875. OHhoceras Dyei'i, S. A. Miller, Cincinnati Quart. Journ. Sci. 
vol. ii. No. 2, p. 125, f. 11. 
1880. Orthoceras Bijeri, S. A. Miller, Joum. Cincinnati Soc. Nat. Hist, 
vol. iii. No. 3, p. 230, pi. vii. f. 7. 
1880. Orthoceras Dyeri, J. F. James, Joum. Cincinnati Soc. Nat. Hist, 
vol. viii. No. 4, p. 238. 
Sp. Char. Section elliptical, somewhat rapidly tapering. Septa 
from 3 to 4 lines distant at a diameter of about IJ inch. Siphuncle 
large, subcentral, somewhat inflated between the septa. Body- 
chamber and surface characters unknown. 
Horizon. Cincinnati Group ( = Lower and Middle Bala?). 
Locality. Cincinnati, Ohio. 
One specimen only in the Collection. 
Orthoceras Mohri ?, S. A. Miller. 
1875. Orthoceras Mohri, S. A. Miller, Cincinnati Quart. Journ. Sci. 
vol. ii. No. 2, p. 124, f. 10. 
1880. Orthoceras Mohri, J. F. James, .Journ. Cincinnati vSoc. Nat. 
Hist. vol. viii. No. 4, p. 238. 
Hp. Char. Section circular. The rate of tapering somewhat 
rapid, about 1 in 6. Septa numerous, rather strongly arched. 
Siphuncle central, inflated between the sej)ta. “ Outer [Borly] 
chamber more than ^ the length of the shell ” {Miller). Surface 
smooth. 
Horizon. Cincinnati Group ( = Lower and Middle Bala?). 
T^ocality. Versailles, Indiana. 
Fairly well represented. 
Orthoceras transversum ?, S. A. Miller. 
1875. Orthoceras transversum, S. A. Miller, Cincinnati Quart. Jcurn. 
Sci. vol. ii. No. 2, p. 129, f. 15. 
