180 ROYAL SOCIETY OF CANADA 



PTYCHOPAEIA Corda. 

 Ptychoparia limbata. n. sp. (PL III., ûgs. la to d.) 



The glabella and cheeks of this species are in low relief, and the 

 dorsal furrows Hghtly impressed. 



The anterior marginal fold is less than half of the width of the front 

 ai'ea of the cheeks. The glabella is cjdindro-conical, and is marked by 

 three flat, obscure furrows. The occipital ring is narrow and crowned 

 by a low tubercle. The tixed cheek has a distinct ocular fillet, and, with 

 the eyelobe, is as wide as the glabella is in front. The posterior marginal 

 fold and furrow are distinctly impressed. The eyelobes are small and 

 sutui'e runs back from them, curving outward in a double curve towards 

 the genal angle ; in front of the eyes the suture runs more directly to the 

 margin. 



In the cheek found loose with this species, the area is about three 

 times as wide as the marginal fold. Only the base of the genal spine is 

 preserved. 



A pygidium found loose with this head has six rings (beside the half- 

 ring) in the axis, and three broad diverging ribs faintly mark the latei'al 

 lobes of the pygidium. There is a faintly marked lateral border and a 

 more distinct anterior boi'der fold. The side lobes of the pygidium are 

 rather flat. 



Sculpture. — This consists of minute granulations. 



Size. — Length of the head-shield, 11 mm. ; width of the middle 

 piece at the eyelobes, 13 mm. ; at the posterior angles, 18 mm. Length 

 of the movable cheek, exclusive of the spine, 8 mm. ; width. 5 mm. 

 Length of pygidium, 4 mm. ; width, 7 mm. 



Horizon. — Found in the limestone bands of the gray shales. 



This species is allied to P. nilcrophthalma (= Anomocare microph- 

 thalmum, Ang.) of the Swedish Cambrian rocks, but differs in its wider 

 free cheek and narrower pygidium. In the wide margin of the head- 

 shield and the flattened border of the pygidium it is like an Anomocare. 

 Its resemblance to this genus will also appear if we compare it with Cono- 

 cephalites (Anomocare) tucer, Bill., of the Vermont Cambrian. (See 

 PI. TV., fig. 8.) 



Ptychoparia Adamsi, Billings sp. var. (PI. IV., fig. 9. 



Conocephalites Adanu^i , Bill., Geol. Vermont, vol. ii., p. 9.5(», fig. 355. 



Ptychoparia Adami, WaXcott, U. S. Geol. Survey Bull. 30, p. 195, pi, xxvi., 

 figs. 1 a to c. 



Ptychoparia Adamsi, Wale, Fauna of Olenellus Zone, p. 649. pi. xcvL, figs, 1 a 

 to c. 



