﻿DEIPIION. 



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in ours, which, from several differences of proportion in all the parts, I suspect to be a 

 different species. If so, I shall call it after the distinguished palaeontologist who discovered 

 the genus. It may be only a local variety. 



The thorax, now for the first time figured, has a narrow convex axis, of ten rings, 

 tapering slowly backward, and strongly distinguished from the gently curved pleurae. 

 These arch a little upward, and at the recurved pointed apices strongly downward, giving 

 a singular aspect, as of the prickles of a Geum or a teazel-head. The pleurae are semi- 

 cylindric, contracted at the base, most convex along the median line, and flatter towards 

 the tips. They are quite separate from each other, not touching, so far as I can see, 

 along the fulcral edge ; nor is there any distinct fulcrum, only a little expansion on the 

 forward edge. We have omitted an enlarged view of the thorax-ring on the plate, and 

 supply it here. 



Deiphon Forbesii. Enlarged view from above, not endwise, of seventh thorax-ring. 



The front pleurae are shorter than those which follow them, to accommodate the former 

 to the shape of the head-spines ; the hinder pleurae, in like manner from the seventh, begin 

 to shorten ; and the last is so short and slender, and so frequently attached to the tail (not 

 connate with it, however, as Barrande supposed and figured it), as to look like a part of 

 that organ. 



Tail — a pair of widely divergent broad-pointed prongs, strongly curved back at the tips ; 

 and more divergent in the adult (figs. 11, 12) than in the younger state (figs. 1, 2, 3). The 

 end is quite truncate, the base of attachment narrow ; and the axis, of three or four rings 

 arranged in a stellate fashion, is depressed below the whole of the general surface. 



Locality. — Wenlock Limestone of Dudley and Wallsall ; Wenlock Shale of Malvern 

 Tunnel. I do not know it elsewhere in Britain. 



Foreign distribution. — Etage E. Bohemia. The genus occurs in Regio D — E. in Sweden 

 (Angelin). 



I do not enter upon the description of those doubtful members of the Cheirurid 

 group — the genera Cybele, Encrinurus, &c, for the reasons before assigned, viz., the 

 imperfection of the materials, and the doubt I still feel whether these genera should not 

 form a distinct family group. I shall also omit the family Acidaspida, the materials for 

 which are more complete, but the knowledge we yet have of them is not so. It is better 

 to leave these, and begin upon those groups of which we have abundant materials. I 

 shall therefore follow on with the families Calymenidce and AsapJiidce. 

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