376 Annals of the Carnegie Museum. 



r. viilcanus liillings. 

 /-*. niercitriiis killings. 

 P. a polio Billings. 

 Section Nieszkoioskia : 

 P. glauciis Billings. 

 P. perforator Billings. 

 P. satyrus Billings. 

 P. iniinitor Billings. 

 /-*. mars Hudson. 



P^amily FHACOPID.-I^: Salter. 



Genus DALMANITES Emmrich. 



Subgenus Ptkrvgometopus Schmidt. 



Pterygometopus annulatus sp. nov. 



Cf. /Herygojnelopiis iallicephaliis Hall. Enund. Clarke. Paleontology of Minne- 

 sota, volume III, part II, page 731, figures 51, 52. 



One of the most common trilobites met with on \'alcour Island is 

 a Dalmanites whose cephalon agrees closely with that oi Pterygometopus 

 calliccphaliis of the Trenton, but associated with it are numerous 

 pygidia whose characters vary considerably in the different specimens, 

 and none of them agree very closely with the pygidium of the Trenton 

 species above mentioned. Heads and tails of this species are common, 

 but no complete specimen has been found, although one specimen 

 shows the pygidium and si.x of the thoracic segments. 



Description. 

 Cephalon. — Cephalon short, broad, gently rounded, with a very 

 short triangular projection in front of the glabella. Glabella shows 

 three pairs of furrows. Frontal lobe large, sloping gently down 

 to the front. Second pair of glabellar lobes strongly angulated, 

 outlined by deep furrows. Second pair of furrows directed forward 

 at about 30°, short, and the lobes back of them, small. J'osterior 

 lobes very small. The posterior part of the glabella differs from that 

 of P. callicephalits in being much narrower. Fixed cheeks bear the 

 genal angles, which are rounded and without trace of spines. Free 

 cheeks small. Eyes large, extending from the neck furrow to the 

 first pair of glabellar furrows. 



