CrepHatopopa.| UPPER PALOZOIC MOLLUSCA. 569 
probable that the species belongs to the subgenus Poterioceras, with which all the other characters agree exactly, 
and better than with any other section of Orthoceras. 
Position and Locality.—Not very uncommon in the carboniferous limestone of Lowick, Northumberland. 
Explanation of Figures.—P1. 3. H. fig. 17, side view of septate portion of specimen (wanting the last 
chamber), reduced one-half linear; fig. 17 @, portion of ditto, natural size, to shew the striation of the surface ; 
fig. 17 }, end view of portion of ditto to shew the difference between the oval septa, and the circular section. 
ORTHOCERAS CYLINDRACEUM (//lem.) 
Ref—Flem. Ann. Philos. Vol. V. t. 31. f. 3. 
Dese.—V ery gradually taperiug ; section nearly circular ; siphon large, nearly central ; chambers numerous; 
septa very slightly waved ; surface very minutely striated transversely. A specimen eight inches long is one 
inch five lines in diameter at the large end, and three lines in diameter at the imperfect small end; another 
fragment nearer the apex five lines in diameter at the large end and three inches long, is only one line and half 
in diameter at the small end ; at from one to two lines in diameter there are three chambers in a space equalling 
the diameter; there are three chambers and a half in a space equal to the diameter in a specimen five lines 
in diameter, and four and a half in a diameter when the diameter is one inch. 
This very slender species much resembles Fleming’s figure of the O. pyramidale, but tapers very much more 
slowly, and has the chambers obviously more numerous. The septa of the O. inequiseptum of Phillips are 
represented considerably closer than in this species. The original Devonshire specimens figured by Sowerby 
in the Geological Transactions (2nd Series, Vol. V.t. 52. f. 6, 7) under the name O. cylindraceum are indeter- 
minable fragments in the collection, and cannot be referred with certainty to this or any other species. 
Position and Locality—Rare in the black beds over the main limestone of Derbyshire; rare in the impure 
limestone of Lowick, Northumberland; rare in the carboniferous shale of Craige, near Kilmarnock. 
OrtHOocERAS (Cycloceras) FLieminet (A/‘Coy). PI. 3. H. fig. 18. 
Ref —MCoy, Ann. Nat. Hist. 2nd Series, Vol. XII. 
Dese.—Very gradually tapering ; section (? broad-oval) ; siphon subcentral, large, slightly eccentric; septa 
numerous, moderately convex, one coinciding with each of the external rings; surface girt with close, obtuse, 
prominent, transverse rings, little more than their own thickness apart, nodulated by about fourteen or fifteen 
strong, longitudinal cost, slightly further apart than the transverse rings (so that the oblong, intervening spaces 
are wider than long) and nearly equalling them in thickness; both transverse rings and intervening spaces 
marked by strong, transverse, imbricating strive, six or seven between the centre of one transverse ring and the 
next. A specimen (fragment), five lines long and two lines in diameter at the smaller end, has twelve rings. 
This species can only be confounded with the O. (C.) rugosum of Fleming, from which it is distinguished 
by its much more numerous and closer rings, fewer and larger longitudinal coste, stronger transyerse strize, and 
large siphon, far removed from the margin. 
Position and Locality —Very rare in the carboniferous limestone of Lowick, Northumberland. 
Explanation of Figures.—P\. 3. H. fig. 18, side view of fragment, natural size; fig. 18 a, surface of 
ditto magnified; fig. 18 4, end view of septum, shewing position of siphon. 
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ORTHOCERAS (Poterioceras) FUSIFORME (Soi.) 
Ref.—Sow. Min. Con. t. 588. f. 1 and 2. 
Dese._—Slender, fusiform, gradually arched towards the apex; lateral outlines gradually tapering from the 
base of the last chamber to the apex, and very slightly tapering from thence to the mouth; dorsal outline 
regularly and gently arched ; ventral outline gradually arched from the base of the last chamber to the apex, 
but very abruptly sloping inwards, with slight convexity from thence to the mouth, which is thus much narrowed. 
Septa very numerous, with a slight sigmoid obliquity on the sides, crossing without wave at a more posterior 
4pn2 
