﻿BRITISH FOSSIL CEPHALOPODA. 69 



BIBLIOGRAPHY OF BRITISH SILURIAN CEPHALOPODS. 



1814. — The first Cephalopod figured or described from British Silurian rocks 

 was that named Orthoceras circulare by Sowerby, in the ' Mineral Conchology ' 

 (PL 60), from Dudley. 



1818. — The next is described in the same work (PL 133). It is Orthoceras 

 annulatum, from the limestone of Coalbrookdale, supposed at the time to be Carboni- 

 ferous, but now known to be Silurian. 



1839. — The Silurian system by R. I. Mfrchison is, however, the startiug-point 

 for the great majority of the species. In the second part, or description of the 

 organic remains, by Sowerby, the following are introduced : — From the Tilestones 

 are Orthoceras semipartitum and 0. tracheale. From the Upper Ludlow, Ortho- 

 ceras striatum, virgatum, ibex, articulatum ; also Cyrtoceras Iwve, since recognised as 

 an Ecculiomphalus. From the Aymestry Limestone, 0. mocktreense, pyriforme, 

 virgatum. From the Lower Ludlow, 0. ludense, gregarium, distans, excentricum, 

 imbricatum, filosum, virgatum, dimidiatum, Jimbriatum, ibex, and pyriforme, as well 

 as the previously described 0. annulatum and the so-called Cyrtoceras loeve; also 

 Phragmoceras arcuatum, ventricosum, compressum, and nautileum, the genus being 

 at the same time introduced and defined, the name being suggested to him by 

 Broderip ; also Lituites articulatus, giganteus, and tortuosus. From the Wenlock 

 Limestone are described Orthoceras Brightii, annulatum, pyriforme, and Lituites 

 Biddulphii and giganteus. From the Wenlock Shale, 0. excentricum., nummularium, 

 attenuatum, virgatum, canaliculatum, jimbriatum, and annulatum. And from the 

 Lower Silurian rocks, 0. annulatum, approximatum, bisiphonatum ; Nautilus undosus, 

 and Lituites cornu-arietis. The genus Gomphoceras is also suggested for some species 

 named Phragmoceras, but having their axis straight. Only a portion of these 

 names are still accepted. 



1843. — Portlock, 'Report on the Greology of the County of Londonderry, and 

 of parts of Tyrone and Fermanagh.' In his descriptive list of fossils he enumerates 

 many Cephalopods. Some he refers to Miinster's Devonian species, as Orthoceras 

 calamiteum, subannulare, subflexuosum, irregulare, regulare; Gomphoceras subpyriforme 

 and subfusiforme, and Phragmoceras Brateri. A few he quotes from Sowerby, 

 including 0. tubicinella, originally described from the Devonian, to which he adds 

 a variety, subnodosum. He records Phragmoceras arcuatum and compressum, Lituites 

 cornu-arietis, Orthoceras Brongniartii (Troost) and lineatum (Hisinger), but the rest 

 he considers new, assigning the following names : — Orthoceras gracile, perannulatum, 

 pomeroense, subcostatum, tenuicinctum, elongato-cinctum, subundulatum, tumidum, brevi- 

 conicum, subarcuatum, complanato-septum, incertum, and Phragmoceras inosquiseptum. 



