19 



tiou to the large pedunculated eyes, over their base, 

 which are nearly in the middle of the cheeks; the antei'i- 

 or branches of the facial sutures converge from the base 

 of the eyes to the front of the glabella ; they then turn 

 suddenly at an angle of 90° downwards, and running 

 parallel in a vertical direction to the marginal edge, 

 which they cut, and then converging, combine into a 

 rostral suture. (PI. i, fig. 17.) 



A flattened space, bordered by a row of tubercles, sur- 

 rounds the base of the eyes ; the distance of the eyes 

 from each other exceeds the extreme width of the gla- 

 bella, and are finely facetted, according to Kutorga. 

 The cheeks are triangular ; and separated in front by a 

 vertical suture, convex and tumid. The occipital fur- 

 row is continuous ; and the occipital ring broadest in 

 the centre, which is smooth, but has a tubercle at 

 each extremity. Hypostoma ovate, rhomboidal, subtri- 

 lobed tubercular and surrounded by a sinuated margin ; 

 its convex extremity very broad, and its cucullated tip 

 buts against a large tubercle, jilaced upon the anterior 

 margin of the head; (pi. i, fig. la,) the wings or apophy- 

 sis of the hypostoma are short and triangularly pointed. 



The thorax has 11 segments ; the slightly convex 

 axis is distinctly bounded by dorsal furrows. The axis 

 joints are somewhat narrower than the pleur?e, and wider 

 on the median line than at their lateral extremities ; 7th 

 and 9tli axis joints (7tli and 10th, according to Salter 

 and Barrande) have on their median line a small spine. 



The pleurse are without grooves, notched at their ends, 

 and usually covered with small tubercles, the pleuree 

 are horizontal half way down, then strongly curved 



