B. Etheridge , Jun. — Contributions to British Pahvontology. 249 
Class Cephalopoda. Genus Orthoceras, Breyn. 
Ortlioceras Brouonianun, p. nov. Plate XII. Figs. loa and 156. 
Stiletto-like Orthoceras, Kev. T. Brown. Trans. R. Soc. Edinb., vol. xsii. pt. 2, p. 362; 
(Compare 0. calamus, de Kon., Descrip. Anim. Foss. Terr. Carb. Belgique, 
p. 506, Supplement, p. 703, pl. 59, f. 2 a-d; 0. reguläre, v. Scbl. Sandberger’s 
Die Yerstein. d. Rhein. Schichtensystems in Nassau, 1856, p. 173, atlas, pl. 20, 
f. 2 ; 0. planiseptatum, Sandb. loc. cit., p. 160, atlas, pl. 17, f . 4 ; 0. acutissimum, 
id. loc. cit. p. 173, atlas, pl. 20, f. 10.) 
Sp. Clmrs. — Shell much elongated, pointed, and stiletto-like, 
tapering very gradually ; section at tke smaller end circular (not 
determinable at the larger end). Septal sutures distant as compared 
with the diameter of the shell, horizontal, not waved ; intervals 
decreasing very sliglitly towards the smaller end ; septa, as denoted 
by the only one visible, somewhat flattened, not very convex. 
Chambers as denoted by the intervals between the septal sutures, 
with the height (vertical) exceeding the diameter (transverse). 
Siphuncle subcentral. The specimen where septate is a fraction 
more than two inches long ; the diameter of the smaller end is as 
near as possible a little less than half a line ; at the upper end 
immediately before the point where it is crushed the diameter is 
about one line and a half. In the space of one inch there are 19 
or 20 chambers. Surface smooth. 
Obs . — For an introduction to this elegant Orthoceras we are in- 
debted to the Bev. T. Brown, M.A., who aptly termed it in liis 
paper “On the Mountain Limestone and Lower Carboniferous Rocks 
of the Fifeshire Coast,” etc., 1 the “ thin stiletto-like Orthoceras,” 
and mentions it as exceedingly characteristic of his Bed F, or 
“ Ardross Limestone,” near Elie. 
In Prof, de Koninck’s Classification of Carboniferous Ortlioceratites 
this species would clearly come under the division “ Orthocerata 
gracilia,” and in form and slendemess resembles the typical species 
of that section, O. Martinianum, de Kon., 2 but the septa are rather 
distant and cannot be described as very close, as in the Professor’s 
species. There is a closer resemblance to his O. calamus ; especially 
to the apical portion represented by Fig. 2 b on the 59th plate of 
the “Animaux Fossiles.” Our form appears to taper at nearly the 
same ratio, but is perhaps thinner and more slender ; the septal 
sutures are about the same distance apart as those of O. calamus, 
and the section is equally circular, but the siphuncle is subcentral 
in position. 
I would also call attention to the resemblance of this Orthoceratite 
to the apical portion of O. reguläre, v. Schlotheim, as figured by the 
Drs. Sandberger, but in this case the septa certainly appear too far 
apart, and, as in the case of Prof, de Koninck’s species, the siphuncle 
is central. O. Brownianum is also not unlike the apical portion of 
O. planiseptatum, Sandberger, but here the chambers are far too broad 
for their height to bear close comparison with the present form. In 
all these cases it must of course be borne in mind that no comparison 
can be made with the large upper ends in the three species, O. cala- 
mus, O. reguläre, and O. planiseptatum, especially in the two latter. 
1 loc. cit. suprd. 2 op. cit. suprä, p. 505, t. 44, f. 4. 
