﻿BEITISH FOSSIL CEPHALOPODA. Ill 



marked transversely at half the distance of the sulci. On one side of one example, 

 from the Wenlock Shale, Builth Bridge, there is, on the cast or inner layer, a 

 broader depression than usual, and on each side the raised lines imbricate towards it, 

 thus facing in opposite directions, and the two nearest are closer together (fig. 10). 

 This may indicate something in the nature of a normal line. The septa are direct 

 and moderately convex, and nearly half the diameter apart. The siphuncle is 

 narrow and central. The largest seen is 3^ inches long, and the greatest diameter 

 seen is 1^ inches. 



Relations. — By some extraordinary oversight the name of 0. dulce has become 

 attached to this species in British collections, and the name has passed into 

 catalogues. 0. dulce has nothing to do with it, being allied to 0. Duponti. I 

 cannot understand how Barrande can call specimens which differ solely from this 

 by showing punctures in the furrows (a character surely not alone sufficient for the 

 separation), by the name 0. striato-punctatum. Miinster distinctly states that 

 between the furrows of his species are " raised lines, with a row of elevated points," 

 a description which would not at all apply to 0. originate. M. Barrande states that 

 he has compared his specimens with some examples from Miinster's locality, and they 

 agree ; in which case the latter cannot be the fossils which that author describes. 

 Our British species of 0. originate do not show any punctures. No other species, 

 when the two layers are seen, can be confounded with this, and they are generally 

 in some manner indicated. 



Distribution. — In the Wenlock Shale of Llanerch (1), of Builth (10), of Welch- 

 pool (1), From the Coldwell Flags (possibly this, 3). From the Lower Ludlow of 

 Ludlow (2), of Downton (1), and of Leintwardine (3). Specimens are in the 

 Museum of Practical Geology, the Woodwardian Museum, and those of Ludlow and 

 Owens College, Manchester. 



Orthoceras Bacchus, Barrande, PI. IX. figs. 3, 4, 5, 6, 7. 



1868. Orthoceras Bacchus, Barrande, ' Syst. Silur. de Boherne,' vol. ii. pi. 270, 271. 



Type. — Section circular, but occasionally elliptic. In the smaller examples there 

 is often a slight curvature. The rate of increase is 1 in 8 or 1 in 9. The body- 

 chamber has a length 1\ times its basal diameter. It has a broad depression 

 below the aperture which is slightly oblique, but simple in outline. The ornaments 

 are of four kinds : 1st, the large longitudinal narrow ribs, which start alone from 

 the apex, and towards the aperture have a furrow on their surface as though they 

 were tubular and worn down ; 2nd, intermediate longitudinal riblets of variable 

 size and number, and occasionally crinkled, some being more predominant, accord- 

 ing to their earlier introduction, and all becoming bifid ; 3rd, pretty regular trans- 

 verse undulations, varying in intensity and dying off with age, — the longitudinal 



