146 CRUSTACEA. 



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 

 CryphauSf and to doubt very much the propriety of separating 

 Eccoptochile 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 ^ Memoirs of the Geol. Survey ' from Sholes 

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

 Spharexochus juvenis (Salter) f, but not alluded to in the text. 



In the limestone of Khiwlas. 



{Col. University of Cambridge.) 



Ceraurus Williamsii (M'Coy). 

 Sp. Char. Cephalothorax semielliptical, length rather more than 

 half the width ; glabella semicylindrical, gibbous, rounded in 

 front, with nearly parallel sides, three nearly equidistant, 

 curved, segmental furrows on each side, the basal pair nearly 

 confluent at their ends with the neck-furrow, inclosing a 

 tumid ovate space on each side, separated by an undivided 

 space about one-fourth of the width of the glabella ; thorax 

 twice the length of the glabella, axal segments large, two- 

 thirds the width of the pleurae, each of which has a very large, 

 diagonally cleft, oblong tubercle at its origin, beyond which 

 there is a neck-like contraction of the margin, followed at one- 

 third from the axis by a hemispherical tubercle about half its 

 diameter distant from the first, beyond which the distal two- 



* Since this was printed, M. de Verneuil advised me to use Eccoptochile 

 as the generic term for this Trilobite, as Green described two generic types 

 under Cryphceus, and it is the second one which is best known under that 

 name in America. 



t Corrected to S. clavifrons (Dal.) in the list of plates prefixed to the 

 same work. 



