78 G. F. MATTHEW: ILLUSTRATIONS OP 



greater. The iuterrupted raised Hues aroiind the dome of the glabella, and the heavy gla- 

 bellar furrows deeply cut arouud the margin of that part of the shield, also distinguish it 

 from the type. 



The young of this variety resemble in form P. Harknessi, Hicks, of the Solva group 

 of Wales. 



Length of the cephalic shield, 26 mm. Width between the sutures, 29 mm. 



Horizon and Locality. In the calcareous shales of Div. 1 c\ at Portland. The type of 

 P. Acadicus is mostly abundant in Div. l.t", at the same place. 



Pauadoxides Abenacus, n. sp. (Plate VII. Figs. lYa, b, c and d.) 



This is the first species with shortened eyelobes thus far recognized in the Acadian 

 measures. The description following applies to the narrow form so far as regards the 

 cephalic shield, and is taken from the shield of an individual of considerably less than 

 full adult size. 



The^head shield between the sutures is more than a third wider than it is long ; it is 

 broadly subquadrate, with a broadly arched front, and having rounded extremities to the 

 anterior margin, a short, moderately arched eyelobe, and sharp triangular points at the 

 posterior angles. 



The anterior marginal fold rolls down in front of the glabella, and laterally is pro- 

 longed into a strong rounded ridge, where, as seen from above, it is much wider than it is 

 in front of the glabella. The flat area is tumid anteriorly, and is separated from the fold 

 by a fiirrow which, toward the glabella, is deeper than the dorsal furrow ; the tumid part 

 of the flat area rises into a sharp ridge towards the front of the glabella. 



The glabella is somewhat longer than wide, its greatest width being about one quar- 

 ter from its apex (front), which is l>roadly rounded, and where it overhangs the anterior 

 marginal fold. The two first glabellar furrows are strongly impressed and go across the 

 glabella, but are fainter at the middle quarter than elsewhere. The first arches backward 

 towards the axial line and the second less markedly so. The second furrow is arched on 

 each side of the axial line, with the convexity on the anterior side. The third and fourth 

 furrows do not cross the glabella, and are quite faintly marked ; neither of these furrows 

 reach the margin of the glabella ; the ends of the fourth pair of furrows are separated by a 

 space about equal to one half of the width of the glabella. 



The occipital ring is nearly straight along the posterior margin in the middle half, 

 and rounded forward at the ends ; the spine or tubercle is about one third from the back 

 of the ring ; the furrow is nearly straight at the lateral third, but is strongly arched for- 

 ward in the middle third, where it is more lightly impressed. 



The posterior margin is arched backward towards the extremity ; the fold is narrow in 

 the inner part, but broader and flattened in the oviter third ; the furrow is distinct and 

 slopes abruptly from the cheek and eyelobe, but more gently from the posterior side. 



The fixed cheek is narrow, the width being only about one half of the length, and it 

 is quadrate behind. The eyelobe is nearly half as wide as long ; it is lunate, with a para- 

 bolic curve on the outer side ; it does not extend so far back as the fixed cheek, and is 

 about one quarter narrower than that part. 



The cephalic shield of the broad form (or of a more mature test) difiers from that 



