﻿184 BRITISH FOSSIL CEPHALOPODA. 



still more clearly the contraction towards the aperture, round which the ribs are 

 more approximate, but otherwise it is simple. The curvature is uniform both here 

 and in septal portions. The peculiar irregular running of the ribs is shown. These 

 are always strong ; but no finer ornaments have been observed. The septa show 

 very great convexity, and lie in the spaces between the ribs, and are thus about 

 I the diameter apart. The siphuncle is often seen small and central. 



delations. — This species has entered into the confusion that has arisen over the 

 curved and straight transversely-ribbed species. First, Sowerby thought it might 

 be the straight portion of his Lituites articulatus — now Ophidiocerds. The distinct- 

 ness of the latter has long been seen. Next, the quite straight Orthocerata were 

 confounded with it, and this was placed with 0. ibex. Now that nearly complete 

 straight shells of the latter have been seen, it is known never to be curved. The 

 ribs too and the circular form of the present species ought easily to separate it. 

 Again, it is similar to the curved shells which may be true Lituites, but is more 

 robust, and the specimens figured prove it to have a quite different aperture. It is 

 indeed a Cyrtoceras, which none of the others are, and it appears to be not 

 an unusual thing, to judge by Barrande's figures, for Cyrtoceraia of this ribbed and 

 mediogastric group to contract in the body-chamber. The present species is very 

 like several figured by that author, but has coarser ribs than any. 



Distribution. — In the Lower Ludlow of Mocktree (3), of Aymestry (1), Dudley (1), 

 and Welchpool (1). 



Position of Sipliuncle not indicated. 

 Cyrtoceras multicameratum, Hall. 



See M'Coy, ' Palaeozoic Fossils,' p. 312, and Salter, ' Cambrian and Silurian Fossils,' p. 37. 



I have not been able to prove to my own satisfaction that this species really 

 occurs in Great Britain. The specimen referred to it by M'Coy, and subsequently 

 by Salter, is in the Woodwardian Museum at Cambridge. It is some curved 

 organism in a concretionary limestone, and its surface is utterly eaten out by atmo- 

 spheric agencies. There appear to be a number of knobs arranged in longitudinal 

 lines, with intervening longitudinal ribs ; but the v hole appearance may be only 

 due to weathering : just so the supposed septa, for between these knobs are trans- 

 verse lines which have been considered to be sutures. The general shape is certainly 

 that of a small Cyrtoceras, or of a small coral, and I see no proof of its being one of 

 these rather than the other. 



This is the only specimen referred to the species I have seen," though it has 

 been recorded from Wrae and Grirvan by Lapworth. The best collection of the 

 fossils from the latter locality having been withheld from my inspection, I am 





