30 CARBONIFEROUS TRILOBITES. 



blunt termination considerably witbin tbe border ; tbe ribs of the pygidium are 

 double and die out before reaching tbe edge of tbe tail-sbield, leaving a somewhat 

 wide smooth margin. Surface of head very finely punctate. 



Formation. — Carboniferous Limestone. 



Localities. — Bolland and Settle, Yorkshire ; Forest of Wyre, Oreton ; Milicent, 

 Clane, Kildare ; Waterford, Clonea ; Derryloran, Tyrone ; Blackrock, Cork ; and 

 Athlone, Ireland. 



Hypostome. — A detached hypostome from Derryloran, Tyrone (see PI. VI, 

 fig. 5), belonging to one of these species of Griffithides, if not to G. globiceps, has 

 very well-marked characters. 



The upper border is strongly arched, the centre is tumid ; the two wings form 

 blunt angles, giving breadth to the attached anterior border ; the sides curve 

 inward almost to the lower end where there is a slight expansion ; the lower free 

 extremity is only half as wide as the upper ; the rim or border is raised and the 

 angles truncated, the inner portion of the lower extremity is slightly raised. 



Of Griffithides globiceps. Prof. Philhps in his ' Geology of Yorkshire ' (1836), 

 vol. ii, p. 240, writes as follows : — " Limb quadrate, with four imbricating striae ; 

 eyes lunate on a globular projection ; head globular. (This agrees better than 

 any other which I have seen with E. Derhiensis of Martin, t. 45, * 1.)" 



General Portlock's description is as follows^ (1843) : — " Glabella short and 

 almost globular in front ; length four tenths, breadth three tenths of an inch ; 

 greatly elevated above the cheeks ; narrowed at the base to less than one half the 

 breadth in front ; cheeks triangular, slightly convex ; eyes short, lunate, connected 

 with the glabella by a projection or nucleus ; no visible reticulation ; the wings end 

 posteriorly in sharp angles, and in perfect specimens appear strongly striated ; the 

 margin is raised above the level of the cheeks ; the neck-furrow is deep ; total 

 breadth of the cephalothorax more than seven tenths of an inch. This is referred 

 to Professor Phillips' species, as it agrees closely with it in the characters of the 

 cephalo'thorax, and is noted by him as occurring in the County of Kildare." 



Dr. Oldham, in the ' Journ. Geol. Soc. Dublin,' 1846 (vol. iii, part 3, p. 188, 

 pi. ii), figures and describes two very perfect specimens of Griffithides globiceps, 

 which by the kindness of Prof. Hull, F.R.S., we are enabled to reproduce on our 

 Plate YI, figs. 1 a, b, and 3. 



Dr. Oldham speaks of this species as one of the most abundant and typical 

 Trilobites of the Carboniferous Limestone." . . . General form, elongated, 

 oval, body contractile, divided into three nearly equal parts by the cephalothorax, 

 thorax, and pygidium ; entire surface marked with minute irregularly disposed 

 granulations, these are only seen in well-preserved specimens. Cephalothorax 

 semi-elliptic ; glabella short, pyriform, very tumescent, approaching to globular 

 ^ ' Geology of Londonderry,' p. 311. 



