Woodward — On Actinoceras. 133 



distinctly describe it, although it seems to me to be necessarily implied in his 

 figures and descriptions. 



Sp. I. P. angiistifolms. Hall (Canada Rep., p. i39 J Quart. Journ., vol. xix , 

 P- '^?)1'> 6g' 7)- Loc. Skiddaw Slates. 



V. — On Actinoceras baccatum, a New Species of Orthoceratite 



FROM THE WOOLHOPE LiMESTONE. 



By Henry Woodward, F.G.S., F.Z.S. 

 [PLATE VIII.] 



THE fossil about to be described was obligingly sent to me by 

 Dr. Bull, of Hereford, having been happily rescued from the 

 remorseless hammer of the road-mender, by Kichard Johnson, Esq., 

 the Town Clerk of that city. It exhibits the shell in section, fractured 

 longitudinally, and embedded in a hard compact mass of dark blue 

 Woolhope Limestone, which may be seen well exposed in situ in 

 the Little Hope quarries, near Woolhope, from whence the block 

 which contains the fossil was derived. Dr. Bull informs me that 

 the Woolhope Limestone from these quarries is always used for 

 road-metal in the surrounding district. 



It is most faithfully delineated (of the natural size) in the ac- 

 companjring lithograph (Plate VIII. ), by the able pencil of Dr. Bull. 



The fossil has been fractured so as to remove the upper surface, 

 exposing seven perfect and two fractured beads of the siphuncle, 

 and giving evidence of ten septa ; the chambers formed by w^hich 

 remain partially hollow and are partly filled by calcareous spar. 

 None of the exterior wall is visible from which the nature of the 

 ornamentation of the shell, if any, might have been ascertained, 

 but the interior portion is so characteristic of the genus that I have 

 no hesitation in referring it to Actinoceras. 



That genus is characterized as follows : — '' Siphuncle very large, 

 inflated between the chambers, and connected with a slender central 

 tube by radiating plates."^ 



Of the species referred to this genus five are British, namely, 



Actinoceras Brongniartii, Portl. Lr. Silurian, Tyrone. 



„ Brightii, Sowerby, U. „ Malverns. 



„ nummularium, Sowerby, „ Tortworth. 



„ giganteum, Sowerby, Carb. L. Yorkshire, etc. 



,, pyramidatum, M'Coy, ,, Ireland. 



The Woolhope fossil most closely resembles A. pyramidatum, of 

 M'Coy, both in the beaded form of the siphuncle and the general pro- 

 portions of the chambers, but the beads of the siphuncle are much 

 less spherical in A. pyramidatum, and the sides of the chambers form 

 a less acute angle at their junction with the outer wall of the shell 

 than in the fossil before us.^ 



1 See'" Woodward's Manual of the Mollusca," p. 58. 



"^ Compare figure on Plate VIII. with M'Coy's figure in Carbonif. Foss. of Ireland, 

 table ^, fig. 5 ; see also Barrande's " Syst. Silur. de Boheme (Cephalopoda) " vol. ii., 

 pi. 232, fig. 11. 



