ORTHOCEKATID^E. 
Orthoceras imhrkatinn, Etheridge (jion Walileiiberg ), Quart. 
Journ. Geol. Soc, vol. xxxiv. p. 607. 
1884. Orthoceras Dann'ni, Whiteaves, Palaeozoic Fossils, rol. iii. pt. 1, 
p. OS, pi. vi. IF. 2, 2 a . — Ci/rfoceras JIt/rice, Whil eaves, loc. cif. 
p. 39, pi. vi. ff. 3, 3 a. 
Orthoceras Darwini . — Fragment of the septate portion of the shell, with a little 
of the test remaining at the upper part of the specimen. Natural size. 
Char. Shell slightly curved. Section elliptical, the ratio of 
the two diameters as 6:7. Rate of increase, measured along the 
broader diameter, 1 in 6. Septa very numerous, slightly undu- 
lating, slowly increasing in distance from about line at the 
narrow end to about 2 lines at the broader end of the fragment. 
Siphuncle central (?). Only a small fragment of the test is pre- 
served in the specimen in the National Collection, and this shows 
that it was ornamented wdth acute longitudinal ribs, about 1 line 
