94 BRITISH CAMBRIAN TRILOBITES. 



Thorax of 12 — 17 segments, with a narrow axis, pleurae endiug in short points. 

 Tail triangular, with a toothed margin. 



I. ? Eurycare, sp. Plate XI, figs. 6—8. 



1864. Olenus (Sphaerophthalmus) flagellifer ?, Salter, Mem. Geol. Surv., Brit. Org. Rem., dec. xi, p. 3, 



pi. viii, figs. 7, 8. 

 1866. Olenus (SphseropMhalmus) flagellifer?, Salter, Mem. Geol. Surv., vol. iii, p. 301, pi. v, figs. 8, 9. 



From Carreg-wen, near Borth, a number of distorted specimens have been 

 obtained which appear to differ from any of the species above described, but which 

 are too imperfect to admit of satisfactory description. I refer them, with doubt, 

 to Eurycare, chiefly on account of the width of the cheeks and the squareness of 

 the glabella. 



They are, for the most part, cranidia of rather large size. In shape they are 

 wide and short, straight or slightly einarginate in front. The glabella is almost 

 square, but with the front somewhat rounded ; two pairs of glabellar furrows 

 appear to have been present, though usually only the posterior pair is distinct ; 

 in most of the specimens the posterior furrows meet across the glabella, but this 

 seems to be the result of compression, for in one which is less flattened than the 

 rest they do not actually meet, but there is .a shallow depression connecting their 

 interior extremities. Neck-furrow well-defined, and on the neck-segment there 

 are indications of a median tubercle. Eye rather large, placed at a distance from 

 the glabella about equal to the width of the latter, and about half-way between the 

 anterior and posterior margins ; ocular ridge long and slightly inclined backwards. 

 Facial suture obscure, but appears to run backwards and outwards from the 

 anterior margin to the eye and then backwards and more strongly outwards to 

 the posterior margin. Fixed cheeks at the eye about equal to the glabella in 

 width, expanded behind. Free cheeks small. 



Thorax with the axis considerably less than the pleura? in width. 



Dimensions. — Before distortion, the width of the cranidium at the base was 

 probably about 8 mm., and its length about 3 mm. 



Of the British forms the one which resembles this most closely is Ctenopyge 

 bisulcata, but both the whole cranidium and the glabella are considerably wider in 

 proportion to their length than in that species, and this does not seem to be due 

 entirely to distortion ; the fixed cheek is also wider and the ocular ridge is less 

 oblique. 



Owing to the imperfect state of preservation, it is scarcely possible to compare 

 this form with the species of Eurycare which have already been described ; but on 

 the whole it seems to approach most nearly to I'J. <tii<jnxtati\m, Aug. 1 In the latter 



1 Angelin, Pal. Scand., p. 48, pi. xx^i, fig. 5 ; Briigger, Die Silur. Etageu 2 und 3, p. 119, pi. xii, 

 figs. 3, 3a; Persson, Geol. Foren. Stockh. Fork, vol. xxvi (1904), p. 517, pi. ix, figs. 9—13. 



