some British Fossil Crustacea. 407 



ments, three similar ones belong to the pygidium, the termi- 

 nal one being obtusely trigonal ; the side lobes are flattened, 

 and more than double the width of the axal lobe ; pleurce nearly 

 straight, narrow, and for the greater part of their length flat- 

 tened, and having a broad, nearly mesial pleural sulcus deeply 

 punctured like the cheeks, dividing each into two parts, the 

 posterior largest and forming a thick, smooth, rounded ridge, 

 bent down and a little backwards in the distal third of its 

 length, swelling to a thick narrow ridge in the middle, the 

 sides and extremity expanding into a broad, thin, foliaceous 

 appendage ; the pygidium terminates in six broad ovate, leaf- 

 like, semimembranous flaps. Length of thorax and pygidium 

 2 inches 2 lines, width 2 inches 3 lines, width of axal lobe 

 6 lines. 



This magnificent Trilobite can only be confounded with the 

 EccoptochUe clavigera (Beyrich sp.), from which it is distin- 

 guished by the much greater width of the lateral lobes of the 

 thorax, and the thin, flat, leaf-like appendages of the pygidium, 

 which in that species resemble thick pear-shaped clubs. A com- 

 parison with the old description and casts published by Green 

 induces me to place this Trilobite in his little-known genus 

 Cryphceus, and to doubt very much the propriety of separating 

 EccoptochUe of Hawle and Corda from it, the only difference 

 being the thickness of the marginal appendage in the Bohemian 

 genus. 



The nearly entire specimen described was collected by Prof. 

 Sedgwick from the Wenlock shale two miles north of Builth. 

 {Col. University of Cambridge.) 



Ceraurus octo-lobatus (M'Coy). 

 Sp. Char. Pygidium transversely elliptical, twice as wide as long, 



two first rings of the axis narrow, distinct, third or terminal 



one large, terminating in four flattened elliptically pointed 



lobes ; two rather larger similar lobes on each side. Length 



2£ lines. 



This curious little species differs from all of this and the allied 

 genera in having the terminal segment of the pygidium quadri- 

 lobate, so that the margin of the pygidium exhibits eight mar- 

 ginal pointed lobes in all. 



It is figured in the f Memoirs of the Geol. Survey ' from Sholes 

 Hook, under the same reference as the cephalic shields there called 

 Sphcerexochus juvenis (Salter)*, but not alluded to in the text. 



In the limestone of Rhiwlas. 



[Col. University of Cambridge.) 



* Corrected to S. clavifrotis (Dal.) in the list of plates prefixed to the 

 same work. 



