20 CARBONIFEROUS TRILOBITES. 



Phillips' specimens. Tlie head (fig. 12) does not, of course, belong to the same 

 individual as the abdomen (fig. 13). Between fig. 13 and the magnified repre- 

 sentation in fig. lea similar resemblance is evident ; in fig. 1 c, however, the 

 margin (limb of Phillips) is not striated; but it may be presumed, from the 

 remarks already made on the strig8 of the pygidia of Trilobites, that there is this 

 difference, simply because in one case the natural cast exhibits the external, in 

 the other the internal surface ; as, however, the term truncatulus seems to have 

 no peculiar reference to this species, it will be named after the gentleman, Mr. 

 Kelly, who supplied the beautiful specimen figured here " (op. cit., pp. 306, 307). 



The beautiful and perfect specimen of Phillijosia drawn on PL III, fig. 1, is 

 the type of that called P. Kellii by Portlock, who thus described it : — ^ 



" Elongated oval ; length '9", breadth 'h" nearly. Cephalothorax elevated, 

 bounded by a flattened margin or wings, which extend at the posterior angles into 

 spines, as far as the fifth thoracic segment. Glabella convex, elongated, even in 

 front with the cheeks, but not extending to the edge of the margin ; rounded in 

 front, at the sides bounded by lines nearly parallel, yet with a slight curvature 

 inwards. Breadth equal to about one third of the total breadth of cephalothorax ; 

 the third or anterior cephalothoracic furrow very faint ; cheeks large, and the eyes 

 being comparatively small there is a large clear space ; eyes do not reach the neck 

 furrow behind, nor extend beyond the third furrow in front ; neck-furrow deep. 



" Thorax. — Axal lobe about equal to lateral lobes in breadth ; axal segments 

 not marked by tubercles, which are arranged, however, along the arched division 

 of each pleuripes, not along the angular division, and continue up to the knee or 

 bend of the segment, which is strongly marked. 



" Pygidium rather wider than long, about fifteen axal and thirteen lateral 

 segments, each marked by six small tubercles, so arranged as to form longitudinal 

 lines on the axal and lateral lobes ; distinct margin. Cephalothorax, including the 

 neck-segment, one third the whole length ; thorax rather less than a third ; 

 abdomen rather more" (op. cit., p. 307). 



On PI. Ill, fig. 8, the artist has endeavoured to represent one of the eyes of a 

 specimen of Ph. gemmulifera, obtained by the late Mr. John Rofe, F.G.S., from 

 the Carboniferous Limestone of Clitheroe, Lancashire. The eye is extremely 

 perfect, and measures one millimetre in breadth and three millimetres in length. 

 The surface is beautifully faceted hexagonally, each facet being convex on its 

 exposed surface. Taking the number of transverse facets at 16, and of longi- 

 tudinal rows at 36, there would be about 576 facets in the eye of this Trilobite. 



1 ' Geology of Londonderry ' (1843), p. 307. 



