318 BRITISH PALAZOZOIC FOSSILS. [CepHaLopopa. 
The extreme fineness of the longitudinal striation distinguishes this species from the O. lineatum of 
Hisinger or O, laqueatum (Hall). 
Position and Locality.—Bala sandstone, Mullock Quarry, Dalquorhan, near Girvan, Ayrshire. 
ORTHOCERAS VAGANS (Sa/t.) Pl. 1. L. fig. 28 and 29. 
ef.—Salter, in Appendix. 
Sp. Ch.—Tube tapering regularly at the rate of one line in one inch, between the diameters of four and 
five lines; the septa are slightly oblique, varying irregularly from two to three lines apart (separate fragments 
seven lines in diameter have them five lines apart, and others one inch one line in diameter have them but two 
and half lines apart); they are very convex, with a small, nearly central siphon, broad oval section, and 
an irregular undulation on each side. 
This species seems principally remarkable for the irregular relative distances of the septa; the surface has 
not been seen. It is impossible to characterize it satisfactorily at present ; still it does not seem referrible to 
any described species. 
Position and Locality.—Very common in the Upper Bala (Coniston) limestone of Coniston, Lancashire ; 
impure Bala limestone of Llwyn-y-ci, N. W. of Bala, and Rhiwlas, N. of Bala, Merionethshire; calcareous 
Upper Bala beds of Cwm of the Cymmerig. 
Explanation of Figures.—P1. 1. L. fig. 28 and 29, natural size, from the limestone of Coniston; 29a, end 
view, shewing form of section and position of siphon. 
ORTHOCERAS? VENTRICOSUM (Sharp Sp.) 
Ref. and Syn. = Creseis ventricosus Sharp. Geol. Journ. Vol. II. t. 18. f. 3. 
Sp. Ch.—Conical, regularly tapering at the rate of two lines in one inch; average length about one inch 
six lines; obscure traces of septa towards the smaller end, and of a thick ridge extending rather more than 
half way from the mouth towards the apex. 
From the appearance of several specimens I think it probable that there were convex rather distant septa 
near the apex, but I cannot be quite sure of the fact: whether the longitudinal ridge is natural or not, is equally 
doubtful, the specimens being all much crushed in the shales in which they occur; the form is a little more 
slender than Count Miinster’s smaller figure of his O. conoideus (Beitr. t. 18. f. 5), to which it is otherwise very 
similar; and the more slender distinctly septate Orthoceratites carinatus of the same author, t. 19. f. 8, has got 
a distinct, very similar, longitudinal keel and elliptical section, with slightly eccentric siphon, agreeing nearly 
with one septum accompanying the present fossil in the schists of Bron Einion. If the appearance of septa be 
deceptive, the species might probably be placed in the genus Theca. 
Position and Locality—Common in the black Upper Bala schists of Bron Einion Quarry, under Pen y Big; 
Upper Bala schists; Upper Bala of Saw Mill, E. of Corwen, Merionethshire ; Upper Bala schists of Builth 
Bridge, Radnorshire. 
Subgenus. CYCLOCERAS (A/‘Coy). 
Ref.—ld. Syn. Carb. Foss, Irel. p. 6. 
Gen. Char.—Shell straight, or slightly curved at the tip, tapering; section circular; girt with prominent 
transverse rings; siphon varying from subcentral to marginal; septa at right angles to the axis of the shell, 
with even edges; surface often sculptured with scaly laminz, or decussated. 
The external characters of this ringed and often sculptured group is so strongly marked, that it forms a 
useful, easily recognised subgenus, proyisionally, apart from the true Orthoceras. 
