HARPES (EOHARPES) YOUNGI. 7 



strongly convex, rising steeply from limb in front and at sides. Glabella sub- 

 conical, blunt in front, widening towards base, strongly elevated above general 

 surface, measuring about three-fourths the length of head-shield (minus limb) 

 and basally rather more than one-third its width; with one pair of short slightly 

 oblique lateral furrows marking off but not separating transverse basal lobes. 

 Axial furrows moderate, with deep sharply curved alar furrow on each side 

 starting outwards at about half length of glabella and sweeping backwards and 

 inwards across cheeks to enclose smooth semi-circular lateral area ("ala") cut off 

 from rest of cheeks. Cheeks swollen, rising steeply on all sides from limb, 

 uniting in broad pre-glabellar portion in front, and divided faintly by weakly 

 impressed concentric " lateral line " into an upper and a lower portion, the latter 

 ( = " cheek-roll ") with very slight independent swelling. Eyes situated a little 

 behind front end of glabella and distant from it less than its width, elevated on 

 low swollen bosses and connected with side of glabella by smooth narrow hori- 

 zontal ocular ridges decreasing in stoutness inwards. Meso-occipital ring rounded, 

 with median tubercle ; occipital furrow strong, prolonged on cheeks, but djnng out 

 before reaching the genal angles. Genal angles elongated backwards into broad- 

 based, slowly tapering, steeply inclined prolongations for about half the length 

 of horns of limb, united to it along lower edge and ornamented with punctse, 

 like those on limb. 



Surface of cheeks behind eyes and above lateral line covered with fine 

 sinuous more or less interrupted nervures radiating outwards and backwards from 

 point of junction of alar furrow with side of glabella, and with small pits placed 

 in the grooves between them. Below the lateral line the nervures are finer, more 

 regular, more numerous and subparallel, running at right angles to the inner 

 margin of the limb, and the pits are rather smaller ; in front of the eyes and on the 

 whole pre-glabellar portion similar radial ornamentation and pitting are present. 

 Thorax and pygidium unknown. 

 Dimensions (of largest example). — 



Length of head-shield to posterior extremities of limb 

 (estimated) 



Width of head-shield including: limb 



Width of limb in front 

 „ „ at sides 



Length of head (without limb) 



Width of „ ( „ „ ) 

 Remarks. — The material on which the above description is based consists of 

 portions of three individuals. 



The largest of them is the best preserved and shows the hollow inner surface 

 of the head-shield with the limb attached, so that it is the interior of the 

 shell and the under surface of the limb which are visible. The natural cast of this 



. 19-00 



mm. 



20-00 





4-00 





4-75 





6-00 





. 10-50 





