﻿180 BRITISH FOSSIL CEPHALOPODA. 



to preservation. The body-chamber has a length of f its basal long diameter. No 

 surface is seen. The septa are distant ^ the mean long diameter in the middle of 

 the side, and the last chamber has nearly the same size as the rest. The sutures 

 are sigmoidal, being concave to the aperture on the inner, and nearly direct on 

 the outer, side. No siphuncle is seen. The greatest length is 2^ inches, and the 

 greatest diameter 1^ inches. From the Lower Ludlow of Leintwardine. In the 

 Woodwardian Museum. 



General Description. — Another example shows the oval section, with the axes in 

 the ratio of 4 to 3 and broadest outside. In this respect it differs from the specimen 

 called by Sowerby Phragmoceras arcuatum (PI. XX. fig. 6a), which is broadest 

 inside, and almost sagittate ; but as all the fossils have obviously been subject to 

 much compression, and probably distortion, this alone cannot be of great con- 

 sequence. The body-chamber in one is as long as its basal diameter, but the septal 

 characters are the same as in the type. If rightly determined, the siphuncle in 

 Sowerby 's specimen is minute and external. 



Relations. — The rate of expansion is not so great as in C. corniculum, and the 

 direction of the septa is different, and the curvature greater than in C. incequiseptum. 

 There are no indications of this being a Phragmoceras. 



Distribution. — In the Lower Ludlow of Leintwardine (3) and of Ludlow (1), and 

 a small specimen possibly of this species (PI. XVIII. fig. 13) in the Wenlock Series ? 

 Dudley. 



Oyrtoceras Uranus, Barrande, PI. XXI. fig. 3. 



1866. Ctrtoceeas Uranus, Barrande, ' Syst. Silur. de Boheme,' vol. ii. pi. 196, figs. 12-18, p. 644. 



Type. — Section subquadrately elliptical, with the long diameter in the plane of 

 curvature. Ratio of diameters 7 to 6. Mean radius of external curvature 2\ inches, 

 the mean diameter being If inches. The long diameter increases at the rate of 

 1 in 4. The surface is ornamented with raised lines which curve backwards, cross 

 the septa, and make a sinus on the front. There are also longitudinal lines which 

 are scarcely to be seen except in the young. The body-chamber is not longer' than 

 the diameter of its base, and the aperture is simple and directly transverse. The 

 septa have a convexity of \ the long diameter. They are distant -g- the long diameter 

 in the middle of the side. The sutures are undulating, in such a way that they 

 would be direct if they did not make a shallow sinus in the middle of the side. 

 The siphuncle has its centre at § the diameter from the inner side. It is very 

 slightly inflated to ^ the long diameter. The largest specimen figured has a length 

 of 4^- inches, and the greatest diameter 2£ inches. From stage E" or Upper 

 Silurian. 



