﻿BRITISH FOSSIL CEPHALOPODA. 89 



ornaments consist essentially of longitudinal, very sharp, raised lines, which vary in 

 size on the same shell, and in some are very feeble, but in others almost rival the 

 ribs, — they are usually two or three times as numerous as the latter ; transverse lines 

 in the interspaces may, or may not be, discoverable. Towards the aperture the 

 stronger ornaments tend to die off. Other specimens show the septa to be close and 

 of little convexity, and the siphuncle to be central. The type is almost the broadest 

 specimen. The length was no doubt more than 6 inches. 



Relations. — This species is certainly very close to 0. gracile, though far less 

 robust. The longitudinal riblets, however, are of a different character, being 

 lamelliform and running evenly over the ribs, though less prominent between them. 

 It is also in some respects similar to 0. dulce (Barrande), if his variety ccelebs, with 

 longitudinal riblets, is rightly included in that species ; but the angular character of 

 the ribs, and their obliquity, among other things, distinguish it from this, as also 

 from 0. pseudo-calamiteum, to which, at first, I referred the specimens. 



Distribution. — In the Upper Llandovery, Llandovery (1) ; in the Wenlock 

 Limestone of Dudley (2), Sedgeley (I), and Malvern (1) ; in the Lower Ludlow 

 of Ledbury (1), and of Usk (4) ; and in the Upper Silurian rocks of the Pen tl and 

 Hills. 



Orthoceras anntjlatum, Sowerby, PI. IV. and PI. VIII. fig. 4. 



1818. Orthoceras annulatum, Sowerby, 'Mineral Conchology,' pi. 133. 



1839. „ „ Sowerby in Murchison's 'Silurian System,' pi. 9, fig. 5, 



p. 632. 

 1852. „ „ M'Coy, ' Palaeozoic Fossils,' p. 319. 



1852. „ „ Hall, ' Palaeontology of New York,' vol. ii. pi. 29, 64, 65, 



pp. 96, 293. 

 1854. „ „ ' Sihiria,' pi. 26, fig. 1. 



1857. „ „ Boll, ' Archiv d. Ver. d. Freunde d. Natur, Mecklenburg.' 



1860. „ „ Eichwald, ' Letbaea Eossica,' vii. p. 1229. 



1867. „ „ Dixon, ' Woolhope Nat. Field Club, Fossil Sketches,' No. 1, 



fig. 5, p. 136. 



1868. „ „ Barrande, 'Syst. Silur. deBoheme,' pi. 290, 291, p. 308. 

 1870. „ „ Barrande, loc. cit., pi. 441, figs. 2-5 (not fig. 1). 



Syn. 1826. Orthoceras undulatum, Hisinger, ' Vetensk. Acad. Handlingar,' tab. vii. fig. 8. 

 1831. „ „ Hisinger, ' Anteckn. V.' tab. 4, p. 6. 



1837. „ „ Hisinger, ' Leth. Suecica,' p. 28, tab. 10, fig. 2. (Not Ortho- 



ceras undulatum, Sowerby.) 

 Not 1836. Orthoceras annulatum, Phillips, ' Geol. Yorks.' vol. ii. pi. 21, figs. 9, 10, p. 239. 

 1837. „ „ Hisinger, ' Leth. Suecica,' p. 29, pi. 9, fig. 8. 



Query 1838. Orthoceras attenuatum, Sowerby, ' Silurian Syst.' pi. 13, fig. 25, p. 632. (Not of 



Fleming.) 

 1849. „ sub attenu athm, D'Orbigny, ' Prodrome.' 



Type. — The original specimen of Sowerby was said by him to come from the 



