OrmiocERA. 
MOLLUSCA. 
39 
12. B. Cornu-Arietus. —The Ram’s Horn Bellerophon, 
pi. XXVI. figs. 31, 32, 33. 
Bellerophon Cornu-Arietus . Sowerby, Min. Conch. V. 
p. 108, pi. 469, figs. 2, 2. Fleming, Brit. An. p. 338. 
Phillips, Geo. of Yorkshire, II. p. 231, pi. 17, fig* 16* Nau¬ 
tilus, lire’s History of Rutherglen, &c. p. 308, pi. 14, fig. 8. 
Shell very thick, smooth, and somewhat compressed ; volu¬ 
tions few, the inner ones very small, rapidly enlarging and 
much expanding towards the aperture; near which, on the back, 
it is provided with a longitudinal, carinated, regular, dorsal 
sinus, which divides the aperture into two lobes; aperture 
large and greatly dilated ; axis solid and very thick. 
The inner volutions are apparent in the cast, fig. 32. 
Found in the Limestone of Kendal; Northumberland ; 
Renfrewshire, and in the Carboniferous Limestone of Lin¬ 
lithgowshire. 
13. B. Ovatus. — The Oval Bellerophon, pi. XXVI. 
fig. 28. 
Ellipsolites ovatus. Sowerby, Min. Conch. I. p. 83, pi. 37* 
Nautilus ovatus. Fleming, Brit. An. p. 231. 
Ovate, gibbose, with a shallow, nearly central umbilicus ; 
inner volutions concealed ; sides of the shell rounded ; sur¬ 
face smooth ; aperture obtusely sagittate, with its sides 
narrow ; greatest diameter thrice the thickness of the shell. 
Found in the Limestone of Black Rock, near Cork, by 
Samuel Wright, Esq. 
Family III.—ORTHOCERATA. 
Shell straight, or nearly so, and destitute of any spiral 
volutions. 
Genus X.—ORTHOCEIIA.— Lamarck. 
Shell elongated, subconic, straight, or slightly arcuated, 
with numerous external, longitudinal grooves ; cells 
formed by transverse septa, perforated by a tube, which 
as either central or marginal. 
SECTION I.-SHELLS STRAIGHT. 
1. O. cordiformis. — The Heart-Shaped Orthocera, 
pi. XXVII. fig 3. 
Orthocera cordiformis. Sowerby, Min. Conch. III. p. 85, 
pi. 247. Fleming, Brit. An. p. 238. Ure, Ilist. Ruther¬ 
glen, &c. p. 306, pi. 17, fig. 1. 
Shell obconical, heart-shaped ; sides convex ; aperture 
round ; surface smooth and plain ; septa numerous, extending 
directly across the shell; sipliuncle not quite central ; the 
tube of which is inflated into a globular form between each 
septum, the last chamber more contracted at its opening than 
at its base. 
This large species measures nine inches and a quarter in 
length, and seven inches at the broadest part. 
Found in the Limestone of the Old Red Sandstone, at 
Closeburn, Dumfries-shire by C. S. Menteith, Esq. 
2. O. gigantea -The Gigantic Orthocera, pi. XXVII. 
fig. 6. 
Orthocera gigantea* Sowerby, Min. Conch. III. p. 81, pi. 
246. Fleming, Brit. An. p. 239. Phillips, Geo. of York¬ 
shire, II. p. 237, pi* 21, fig. 3. 
Shell straight, gradually tapering; finely striated; aperture 
oval, somewhat more than eight inches in diameter; septa 
direct, deep, and numerous ; sipliuncle situate at a little 
distance from the centre. 
This gigantic species is supposed to grow to the extent of 
eight feet, and is, consequently, the largest of ail the known 
testacece. The shell is about a quarter of an inch in thickness. 
This magnificent fossil was discovered by Charles Stewart 
Menteith, Esq. in the Limestone on his estate of Closeburn, 
Dumfries-shire, and has since been met with at Flasby, and 
at Bolland, Queen’s County, Ireland. 
3. O. angularus.—T he Angular Orthocera, pi. XXVII. 
fig. 5. 
Orthoceras ungulate . Phillips, Geo. of Yorkshire, II. p. 
238, pi. 21, fig. 4. 
Shell subcylindrical, with a few longitudinal furrows ; septa 
placed very distant. 
Found at Bolland, Queen’s County, and at Iligh-Green- 
Wood. 
4. O. inequiseptus. —The Inequally-Partitioned Ortho¬ 
cera, pi. XXVII. fig. 7* 
Orthoceras inequi septum. Phillips, Geo. of Yorkshire, II. 
p. 238, pi. 21. fig. 7* 
Shell straight, gradually tapering ; septa unequal, very 
distant in the young shell; section circular. 
Found at Bolland, Queen’s County. 
5. O. --The Reticulated Orthocera, pi. 
XXVII. fig. 8. 
Orthoceras reticulatum. Phillips, Geo. of Yorkshire, II. 
p. 238, pi. 21, fig. 11. 
Shell elongated; septa distant; surface annulated, and 
reticulated with moniliform lines; sections circular. 
This figure is taken from a cast. 
Found at Bolland, Queen’s County. 
6. O. ciRcuLARis.—The Circular Orthocera, pi. XXVIII. 
fig. 2, 3. 
Orthocera circularis. Sowerby, Min. Conch. I. p. 133, 
pi. 60. fig. 6, 7* O. convexa . Fleming, An. Phil. V. p. 202, 
pi. 31, fig. 4. Ih. Brit. An. p. 238. 
Shell nearly cylindrical, or slightly tapering; partitions 
thin and concave, approximate, being about the sixteenth of 
an inch distant .from each other, with their edges even; 
sipliuncle situate about midway between the centre and the 
margin ; diameter of the large end about an inch. 
Found in the Carboniferous Limestone at Dudley. 
7. O. cincta. — The Girdled Orthocera, pi. XXVIII. 
fig. 4. 
Orthocera cincta. Sowerby, Min. Conch. VI. p. 168, pi. 
588, fig. 3. Phillips, Geo. of Yorkshire, II. p. 237, pi* 21, 
fig. 1. 
Shell elongate, almost cylindrical; surface covered with 
numerous sharp, somewhat undulous, annular stria*; siphun- 
culas central; septa rather concave and distant ; section 
very slightly ovate. 
Found at Preston ; Flasby ; Closeburn, Dumfries-shire, and 
Bolland, Ireland. 
8. O. B reyn 11.—Breyn’s Orthocera, pi. XXVIII. fig. 5. 
Orthocera JBrcynii. Martin, Pet. Derby, pi. 39, fig. 2. 
