40 
Sowerby, Min. Conch. I. p* 102, pi. GO, fig. 5. Phillips, 
Geo. of York. II. p. 238. 
Shell cylindrical, elongated, tapering gradually; septa 
numerous, ovate, very oblique and slightly concave, approxi¬ 
mate and shallow ; siphuncle placed in one focus between the 
centre and the margin; outer shell very thin and plain; 
section of an elongated oval form. 
Pound in the Derbyshire Limestone ; Kulkeagh ; and 
Bowes. 
9. O. conic a. —The Conical Orthocera, pi. XXVIII. fig. 
6, 7. 
Orthocera co?iica. Sowerby, Min. Conch. I. p. 131, pi. GO. 
fig. 1, 2, 3. Fleming, Brit. An. p. 238. 
Shell elongated, conical, smooth ; aperture ovate ; chambers 
numerous, increasing in depth with the size of the shell; 
septa with even margins, and regularly concave surfaces, 
and doubly distant from each other at the broad than at the 
narrow extremity ; siphuncle small, oval, and almost close to 
the margin. 
Fig. 7- represents the convex side of one of the septa. 
Found in the Alum Clay at Whitby, by the Dowager 
Marchioness of Bath. 
|fl|10. O. undulata. —The Waved Orthocera, pi. XXVIII. 
fig. 9* 10. 
Orthocera undulata . Sowerby, Min. Conch. I. p. 130, pi. 
59. Fleming, Brit. An. p. 238. Phillips, Geo. of Yorkshire, 
II. p. 238, pi. 21, fig. 8. 
Shell oval, tapering considerably; thin, smooth; partitions 
numerous, nearly parallel, only slightly oblique, and a little 
concave; their edges ascending, oval, with a wave on each 
side, and all equidistant, five or six to an inch ; siphuncle 
situate near the thicker end, at about a sixth part of the 
diameter from the side of the shell, its size being about the 
tenth of an inch ; section of a broad oval form as in fig. 10. 
Found in the Carboniferous Limestone at Scaleber, near 
Settle, Yorkshire ; Castleton, and Cumberland. 
11. O. annulata. —The Ringed Orthocera, pi. XXVIII. 
fig. 11, 12. 
Orthocera annulata . Sowerby, Min. Conch. II. p. 77, 
Fleming, Brit. An. p. 239. Phillips, Geo. of Yorkshire, 
p. 239. 
Shell tapering, subcompressed, with strong, slightly oblique, 
equidistant annulations, and minute, transverse, undulating 
striae; a space equal to about four rings is plain near the 
aperture, which is situate in the thicker end, within which 
the siphuncle is placed, a little way from the side of the 
shell; section a little oval, (fig. 12.) 
Found in the Carboniferous Limestone of Colebrookdale, 
Shropshire ; Bowes ; Kulkeagh ; High-Green-Wood, and 
Northumberland. 
12. O. laterale. — The Lateral Orthocera, pi. XXVIII. 
fig. 14. 
Orthocera laterale . Phillips, Geo. of Yorkshire, pi. 21. 
fig. 8. 
Shell tapering, smooth, slightly compressed, with equi¬ 
distant, wide-set, somewhat oblique septa, their sides slightly 
arcuated ; section a little ovate. 
Found at Bolland, Queen’s County. 
13. O. Steiniiaueri. — Steinhauer’s Orthocera, pi. 
XXVIII. fig. 15. 
Orthocera Steinhaueri . Sowerby, Min. Conch. I. p. 132, 
Orthocera. 
pi. GO. fig. 4. Fleming, Brit. An. p. 239. Phillips, Geo. of 
Yorkshire, II. p. 238, pi. 21, fig. 5. 
Shell circular, very concave, with thin margins, even 
edged, wide, elongated, tapering very gradually; with very 
parallel and^regular transverse striae ; septa distant; chambers 
very deep ; siphuncle rather large, situate close to one side; 
section circular. 
Discovered, by the Rev. II. Steinhauer, in Limestone on 
the Broadford Road, and has been met with at Bolland, and 
in Coal Shale at Halifax. 
14. O. striata. — The Striated Orthocera, pi. XXVIII. 
fig. 17. 
Orthocera striata , Sowerby, Min. Conch. I. p. 129, pi. 58. 
Fleming, Brit. An. p. 239* lb. Wernerian Mem. III. p. 9G. 
Shell nearly cylindrical, and tapering very gradually ; the 
whole surface longitudinally striated ; aperture oval, about a 
third broader than wide; septa very thin, numerous, but 
widely set; chambers deep; siphuncle large and nearly 
central ; greatest known length eleven inches. 
Discovered in the Black Rock Transition Limestone, near 
Cork, and in the Clay Slate of the same formation, at the 
Cove of Cork. 
SECTION II.—SHELLS ARCUATED. 
8 15. O. pyriformis. —The Pear-shaped Orthocera, pi. 
XXVII. fig. 1, 2. 
Orthoceras pyriforme. Phillips, Geo. of Yorkshire, II. 
p. 238. pi. 21, fig. *14, 15. 
Shell pyriform, tumid towards the aperture, and arched 
towards the smaller end; smooth ; section oval, siphuncle 
situate at one-third of the diameter from the edge. 
Professor Phillips says, “ In the specimen figured the 
large projecting plate, with its plane parallel to the axis, (as 
in our fig. 2. pi. XXVII.) and to the longer diameter of the 
shell, is covered on the convex side by a white, laminated, 
friable inner shell, very analogous to the “ bone” of Sepia 
Officinalis, and to the lower laminae of Belemnites quadratus. 
L Found at Bolland and Kildare, Ireland. 
1G. O. fusiformis. — The Spindle-Shaped Orthocera, pi. 
XXVIII. fig. 1. 
Orthocei'a fusiformis . Sowerby, Min. Conch. VI. p. 167, 
pi. 588, fig. 1, 2. 
f Shell arcuated, fusiform, smooth, round, and tapering 
rapidly towards the smaller end, and slightly towards the 
broader one ; siphuncle almost central; outer chamber large. 
Found in the Limestone at Bolland, Queen’s County, 
Ireland, and in similar Limestone near Preston, Lancashire. 
This shell is somewhat allied to the preceding. 
17- O. paradoxic a. — The Paradoxical Orthocera, pi. 
XXVII. fig. 4. 
Orthocera paradoxica f Sowerby, Min Conch. V. p. 81, 
pi. 457. 
Shell lanceolate, triangular, flattened in front, with the edges 
projecting a little, and producing a gentle concavity ; sides 
convex, and somewhat dissimilar ; aperture forming an almost 
equilateral triangle, with sides somewhat rounded, and slightly 
hollowed in front; the siphuncle almost central, but placed a 
little'nearer the front. 
Found in the Mountain Limestone of Ireland. 
18. O. Gesneri. —Gcsner’s Orthocera, pi. XXVII. fig. 9. 
MOLLUSCA. 
