568 BRITISH PALAXOZOIC FOSSILS. [CEPHALOPODA. 
section is as 100 to 85. A specimen five inches long is one inch three lines wide at the large end, and two 
lines wide at the apex, the dilated part of the siphon at the latter point equalling the whole diameter of the 
shell, but being only five lines wide at the anterior end, where two chambers occupy a space of slightly less than 
half an inch, while six chambers occupy the same space at the smaller end. 
The internal structure of the siphon is that of Actinoceras of Stokes, though it is marginal in position, and 
the septa are oblique. Sowerby’s figure under this name has the septa too oblique and too close to agree 
accurately with the species. 
Position and Locality—Very common in the red carboniferous limestone of Closeburn, Dumfriesshire ; 
rare in the dark carboniferous limestone of Isle of Man; common in the black beds overlying the main carbo- 
niferous limestone of Derbyshire, more rare in the underlying white beds ; not uncommon in the dark carboni- 
ferous limestone of Lowick, Northumberland. 
ORTHOCERAS (Poterioceras) CORDIFORME (So7.) 
Ref.—Sow. Min. Con. t. 247. 
Desc.—Very broad, ovate, short ; chambered portion very rapidly tapering, obtusely conical; last chamber 
slightly shorter than the chambered part, abruptly constricted to a short narrowed neck near the mouth; 
greatest width near the last septum. Length of small specimen, imperfect at the apex, nine inches, width 
(probably increased from compression) seven inches, width of mouth five inches, uence of the septa from each 
other five to six lines, length of perfect last chamber four inches. 
This species grows very much larger than the above measurements, which are taken from a specimen from 
which probably nearly two inches of the posterior end is absent, Mr Sowerby’s figure giving very nearly the 
true proportions of the septate part. I am unable to say how much of the obvious compression of our specimens 
is natural ; one of them shews very distinctly the new character of the narrow, contracted, neck-like mouth. I 
have not ascertained the position of the siphon, which, according to Mr Sowerby, is inflated between the septa. 
Position and Locality —Rare in the carboniferous limestone of Lowick, Northumberland. 
OrTHOCERAS (? Poterioceras) CORNU-VACCINUM (Jé*Coy). PI. 3. H. fig. 17. 
Ref —M'Coy, Ann. Nat. Hist. 2nd Series, Vol. XII. 
Desce.—Conical, rapidly tapering to an obtusely rounded point, very slightly arched; section perfectly 
circular throughout ; septa very oblique, flattened, slightly convex, moderately approximate, extending much 
farther forward on the inner side of the general curve than on the outer or convex aspect, the lateral edges being 
very slightly sigmoidal; on account of their obliquity the septa are broad-oval in form, the longest diameter being 
in the antero-posterior direction ; siphon large, about its own diameter within the outer edge (corresponding with 
the convexity of the general curve of the shell). Surface horny in appearance, marked with irregular, scratch- 
like, longitudinal markings, and fine, nearly regular, transverse, impressed strixe, separated by rather wider, 
flattened spaces; thirteen transverse strize in two lines at an inch and quarter in diameter, about twenty in 
the same space at nine lines in diameter. Length of average specimen five inches nine lines; two inches three 
lines in diameter at the anterior end, and regularly tapering to the obtusely pointed apex in the above length ; 
average distance of the last few septa two lines. 
The above measurements are of average-sized specimens, although examples occasionally occur a couple 
of inches longer; the peculiar, slightly curved, obtusely pointed, rapidly tapering form, and peculiar, horny-looking 
texture, have suggested the specific name. The only described fossil it has any resemblance to is the Cyrtoceras 
Verneuilanum of de Koninck (Anim, Foss. Bel. t. 48. f. 6), but is easily distinguished by that species having a 
broad-oyal, transverse section, while the section of the present fossil is perfectly circular, and the septa, which 
from their obliquity appear oval, have their long axes placed in the opposite direction; the curvature is 
also less in our fossil. Some of the specimens shew a very slight contraction at the mouth, which renders it 
