﻿80 BRITISH FOSSIL CEPHALOPODA. 



figured, the siphuncle appears to be nearly marginal, and its elements globular. The 

 specimen figured in PI. XYIII. fig. 12, shows similar ornaments and rate of increase, 

 but this may be due to flattening, and the specimen may possibly be a Gomphoceras. 

 If it really belongs to the present species, the excentric siphuncle, -5- from the circum- 

 ference on the long diameter, is confirmed, and the septa shown to be almost flat, 

 and to have vascular markings connected with two small pits on the surface. The 

 tendency shown by the shell to be contorted in youth, as seen in PI. XVIII. fig. 11, 

 might lead some examples, such as that figured on PI. XIX. figs. 4, 4a, to be taken for 

 Cyrtoceras ; but the resemblance to the type is too great, in shape, ornaments, septa 

 and siphuncle, to admit of its separation, allowance being always made for compres- 

 sion, which produces an apparent curvature. The largest example is If inches in 

 length and extreme breadth. 



Relations. — Nothing British is in any way comparable with this, but Barrande's 

 species, Cyrtoceras cemulus, is very like the young form. 



Distribution. — The type is from Upper Silurian Beds of Scotland, called Llan- 

 dovery Beds. The specimens examined are from the Wenlock Limestone and Shale 

 of Dudley (3) and of Ledbury (1), and from the Lower Ludlow of Aymestry (1). 



2. Orthoceeas xit, Blake, PL XYIII. fig. 9. 



Type. — The section is probably compressed, but is now elliptic with the axes in 

 the ratio of 3 to 2. There is considerable curvature on one side, of minimum radius 

 1 inch, but the other side is straight, or nearly so. The body-chamber, which has a 

 length one and a half times its longer basal diameter, and ends with a simple aperture, 

 is cylindrical ; the septal portion of the shell rapidly tapers off to a much smaller 

 diameter, the end being probably lost. The surface is smooth, except for lines of 

 growth. The septa are slightly oblique, sloping backwards towards the more convex 

 side, and are distant about \ the mean diameter. No siphuncle is seen. The 

 greatest diameter is f- in., and the length 13 lines. From the Wenlock Shale of 

 Dudley. In the British Museum. 



Relations. — This small and solitary ill-preserved specimen is of importance, as 

 indicating a second brevicone Orthoceras, or perhaps Cyrtoceras, in British rocks. 

 It is not unlike Barrande's 0. semisecans, except for the, direction of the septa, nor 

 to some of his figures of small Cyrtocerata, but until further data are forthcoming it 

 is safer to quote it under a distinct name. 



3. Orthoceras hungaricum, Blake, PI. XYIII. fig. 8. 



Type. — The section is elliptic, the diameter being in the ratio of 6 to 5 ; the 

 apical angle is about 38°, the shell commencing nearly at the apex. The body- 

 chamber is a little longer than its breadth, and is nearly f of the whole shell. The 



