﻿194 BEITISH FOSSIL CEPHALOPODA. 



longest in the plane of symmetry. The dorsal aperture is fourfold ; each lobe is 

 rounded, the most dorsal pair the largest. The greatest transverse diameter of this 

 aperture is 16 lines to a ventro-dorsal of 7 lines. The passage has a length of 14 

 lines, and is narrow. The highest point of the shell lies near the centre of the 

 dorsal aperture. There are no ornaments remaining on the surface, but the last 

 chamber has a series of crenulations of the usual character. The septa have very 

 little convexity. They are ^ the largest diameter apart, but the last is of half the 

 usual size. The sutures have a very slight obliquity, rising to the dorsal side. 

 The siphuncle is not accurately seen : probably it is central ; but if not, it must be 

 towards the ventral side. The greatest length is 4^- inches, and the greatest diameter 

 nearly 3 inches. From the Lower Ludlow of Ludlow. In the Ludlow Museum. 



General Description. — It is in the type alone that the distinguishing characters 

 presented by the aperture are seen. Other examples might have been referred to 

 G. pyriforme, by allowing a little latitude to that species. The section of such is a 

 little more elliptic, having the axes in the ratio of 4 to 3 ; also the rate of increase is 

 more rapid, 2 in 3. The body-chamber has its greatest width in the middle of its 

 length. The septal characters are as in the type. One example shows the crenula- 

 tions on the last chamber. This is one of those species which, having one side far 

 more convex than the other, one is tempted to call a Phragmoceras, but yet it is 

 certainly a much closer approach to such a form as G. ellipticum than to P. ventri- 

 cosum, the commonest types of the respective genera. 



Relations. — The differences between this and G. pyriforme have already been 

 indicated. Its nearest ally among Bohemian species is a small form called 

 Phragmoceras discrepans ; the general form and position of the aperture is very 

 faithfully repeated in this, but it has only half the linear dimensions, besides which 

 there are some minor points which give it a different aspect. In our species the 

 body-chamber is broader compared to its length ; the convexity on the ventral side is 

 much greater, so that the smaller aperture is on the upward slope, and not on the 

 ventral border, and the sutures are more curved. While, therefore, we may look 

 on our species as the representative of the Bohemian, reaching a much finer growth, 

 it seems worth while to signalise it by a special name. The name selected had been 

 placed by Salter on the type specimen in the Ludlow Museum. 



Distribution. — In the Lower Ludlow rocks of Ludlow (1) and Ledbury (2), and 

 possibly also of G-arcoed, Usk (1). 



Gomphoceras eta, Blake, PL XXII. figs. 5, 5a. 



Type. — The section is elliptic, the axes being at the maximum 23^ lines and 



21 lines, the longer in the plane of symmetry. The curvature on the dorsal side is 



uniform, the mean radius being 2^- inches; on the ventral side the edge is nearly 



straight to the body-chamber, when it becomes of considerable convexity, of radius 



