﻿108 BRITISH FOSSIL CEPHALOPODA. 



possibly of 0. coralliforme ; its riblets are \ of a line apart, and the transverse lines, 

 which are convex towards the aperture, are of the same size. It is from Lower 

 Silurian rocks. 



Relations. — "Wahlenberg's original description of this shell being unaccompanied 

 by a figure, authors have generally referred to Hisinger's ' Petrificata Suecana ' as 

 giving its characters. Unfortunately Hisinger describes it as having a lateral 

 siphuncle, and draws a figure in which it stands at some distance from the centre. 

 Whether there is actually a different species with a siphuncle in this position, with 

 comparatively few ribs, and probably other distinctions, or whether the supposed 

 position of the siphuncle is due to the same distortion that has produced the curvature, 

 I cannot say ; but no specimens in British collections that I have seen, of either 

 variety, show a siphuncle that is not close to the central line. Ours, therefore, is 

 Wahlenberg's true species, whatever Hisinger's may be. As 0. canaliculatum was 

 separated from 0. angulation on account of the supposed lateral siphuncle of the 

 latter, it must now fall as a synonym. The simplicity of the ornaments, both large 

 and small, distinguishes this species from others of the longitudinally ribbed group, 

 though towards the apex they become so close as to have a resemblance to older 

 portions of such shells as O.filosum and 0. originale. The 0. princeps of Barrande 

 may be an aged example of one variety, and some specimens of 0. doricum could 

 not be distinguished from this species. The specimen he figures from Sweden 

 as belonging to it differs in having, like 0. Bacchus, a number of parallel 

 intermediate riblets. 



Distribution. — This is a very widely distributed species ; but though I have seen 

 one fragment from the Upper Bala of Coldwell that might be referred to this, and 

 the young specimen in the Lower Silurian of Tipperary, well-authenticated speci- 

 mens are confined to the Upper Silurian. It occurs in the Woolhope Beds at 

 Malvern (4) ; in the Wenlock Shale of Ledbury (1), Dinas Bran (1), and Builth (1) ; 

 and in the Denbigh Flags, Llangynyw ; in the Wenlock Limestone of Dudley (15 

 and var. 1), Donnington (1), Nantglyn (1), and Malvern (1) ; in the Lower 

 Ludlow of Dudley (2), Mocktree (5), and Ledbury (10); Llangadock (3), Llan- 

 gibby (1), and Garcoed, Usk (1) ; in the Aymestry Limestone at Mocktree (1) and 

 Usk (2) ; in the Upper Ludlow of Ludlow (5), Presteign (1), Malvern (2), Pilliard's 

 Farm (5), Woolhope (1), Shropshire (1), Brigsteer, Kendal (3, also var. 1), and 

 Underbarrow (1). Also from the Upper Silurian of Llanbaddock (4), in Kerry (2), 

 Gal way (2), the Pentlands (1), and Kirkcudbright (1). 



It has also been recorded by Murchison from the Upper Ludlow of Abberley ; 

 by M'Coy, from the Wenlock Shale, Welchpool, and Bala Shale, Builth ; by Salter, 

 from Bala Shale, Ardwell, also from Lower Ludlow, Killington ; by Phillips, from 

 Marloes, Llandeilo, and Malvern ; by Lapworth, from the Middle Silurian, Girvan ; 

 by Hughes, from the Coniston Flags ; by Harkness and Nicholson, from the Grapto- 



