LEPTOPLASTUS. 89 



but neither of these differences appears to be of much importance, and the absence 

 of the tubercle is probably due to the imperfect state of preservation. 



The species is characterised especially by the width of the fixed cheek at the eye 

 and the very strong emargination of the anterior border. In Gt. dim-fa the fixed 

 cheek is also wide, but not quite so wide as in this form, and moreover, the front 

 margin appears to be nearly straight. 



Horizon and Localities. — Upper Lingula Flags: Moel Gron ; Malvern. 



7. Ctenopyge directa, sp. nov. Plate X, fig. 11. ; Plate XI, fig. 1. 



Only the cranidium is known; almost straight in front. Glabella slightly 

 tapering forwards, rounded in front, reaching the margin; anterior glabellar furrows 

 absent, posterior pair strongly marked, oblique, meeting across the middle line ; 

 neck-furrow well defined, somewhat shallower in the middle ; neck-segment with a 

 large median tubercle, probably the base of a spine. Eyes placed about half-way 

 between the anterior and posterior margins, distant from the glabella considerably 

 more than the width of the latter ; ocular ridge curved, almost at right angles to 

 the axis. Facial suture beginning a little to one side of the glabella, curving back- 

 wards and outwards to the eye, and behind the eye obliquely backwards and out- 

 wards to the posterior margin. Fixed cheeks at the eye about one and a quarter 

 times the width of the glabella, behind the eye about one and a half times the 

 width of the neck-ring; posterior margin fairly straight. 



Dimensions. — Cranidium (Plate X, fig. 11) 4 mm. long, 9'4 mm. wide at 

 posterior margin. 



The special features which distinguish this form from most of the other species of 

 the genus, are the greater width of the fixed cheek at the eye, and the curved ocular 

 ridge, which is more nearly at right angles to the axis than in any other British 

 Ctenopyge. except Gt. teretifrons. The width of the fixed cheek at the posterior 

 margin remains about the same as in Gt. bisulcata, Gt. falcifera and Gt. pecten, and 

 thus the posterior branch of the facial suture runs more directly backwards than in 

 those species. 



From Gt. teretifrons it is distinguished by the straight front margin and the 

 more tapering glabella ; moreover, the fixed cheek is not quite so wide as in that 

 species and the posterior margin is straighter. 



Horizon and Locality. — Upper Lingula Flags : Malvern ; Dolgelly. 



Genus LEPTOPLASTUS, Angelin. 



In Leptoplastus and Eurycare, as in Sphcerophthalmus and Ctenopyge, the genal 

 spines spring from the middle of the external margin of the cheeks. In the first 

 two, however, the pleurae end in short points ; in the last two, at least in the 



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