320 BRITISH PALAZOZOIC FOSSILS. [CerHatopopa. 
diameter of eight lines), with occasional abrupt diminutions of diameter; girt with prominent, narrow, round, 
slightly oblique rings, about two-thirds of a line thick and four in the space of half an inch, at a diameter of 
eight lines, less than five in the same space (and same specimens), with a diameter of four and half lines; 
inter annular spaces concave; section broad-oval; surface with extremely fine, equal, longitudinal strize, about 
ten in one line; septa one between every two rings; siphon a little eccentric. 
It is obvious, from the above description, that the character is not of any value, which led Mr Sowerby 
to separate his O. articulatum from his O. Ibea, namely, the relation between the distance of the rings and the 
diameter of the tube, as our specimens prove that the first does not vary in proportion to the latter. The 
longitudinal striation is so fine that in most specimens it can only be detected by the lens with great difficulty 
in specimens preserved in sandstones—many specimens appearing smooth except perhaps in some small portion ; 
in limestone specimens the striation is distinct. The minute striation of the Hortolus Ibex is transverse as well 
as that of the O. tracheale (Sow. =O. perelegans Salt.), which is otherwise almost identical in appearance 
with this. Towards the small end a few transverse strize appear on each ring decussating the longitudinal ones. 
Specimens from the Coniston limestone differ in haying the longitudinal striation slightly flexuous and of 
irregular thickness. 
Position and Locality —Common in the Upper Ludlow rock of Benson Knot, and Kirkby Moor, Kendal, 
Westmoreland ; Coniston (Bala) limestone, Coniston, Lancashire. 
OrtTHOCERAS (Cycloceras) ? SUBANNULATUM (Miinst. Sp. 
J / 
Ref. and Syn. = Orthoceratites subannulatus 1d. Beitrage zur Pet. t. 19. f. 3. 
Sp. Ch.—Tube tapering at the rate of two lines in two inches, at the diameter of nine lines; section 
broad-oval ; siphuncle very slightly eccentric ; septa moderately concave ; surface girt with close, obsolete, little- 
elevated, slightly oblique rings, with a widely-rounded upper and lower curve, three in three lines, at a diameter 
of seven lines, four in six lines, at the diameter of one and half inches, with parallel, strong, subimbricating 
strize, four or six in the space of one line, in a diameter varying from four lines to one inch nine lines. 
On comparison with authentic specimens of Count Miinster’s species from his locality of Elbersreuth, 
I can find no difference, on the most careful comparison between them and our Silurian specimens. I find that 
his species has the section not circular, but slightly oval as in ours, and the siphon not perfectly central. The 
species, as he notices, is easily distinguished from the Orthoceras annulatum of Sowerby by the very much 
flatter and more approximate rings. The slightly marked approximate rings and much coarser and less 
numerous parallel strize, and more rapidly tapering figure, distinguish it from the Orthoceras (Cycloceras) 
perelegans (Salt. = O. C. tracheale Sow.) 
Position and Locality.— Not uncommon in the Upper Bala flags of Coldwell, Westmoreland ; in the dark 
flags on the road from Coniston to Hawkshead, Lancashire, in Upper Bala (Coniston flag) at Helms Knot, 
Dent; Upper Ludlow rock of Brigsteer, Kendal, Westmoreland; black Upper Bala shale, Builth Bridge, Rad- 
norshire. 
Orraoceras (Cycloceras) TENUIANNULATUM (J/°Coy). PI. 1. L. fig. 31. 
Ref.—1d. M°Coy, Ann. Nat. Hist. 2nd Series, Vol. VII. p. 46. 
Sp. Oh.—Nearly cylindrical (tapering half a line in two inches at a diameter of six lines) ; rings narrow, 
sharply-defined, half a line wide, slightly oblique, six in half an inch at the above dimensions ; surface with 
very minute, longitudinal, equal strize, twelve or fourteen in the space of one line; towards the small end a few 
circular striae on each ring decussating the longitudinal lines. 
This species differs constantly from the O. (Cycloceras) Ibex by the narrower and more sharply defined 
rings, and their considerably greater number in a given space in specimens of the same size ; the longitudinal 
striation is even finer than in that species. 
Position and Locality—In the green Lower Ludlow mudstone of Green Quarry, Leintwardine, Shrop- 
