NO. 7 PTYCHOPARIID TRILOBITES — RASETTI 27 



collected by the writer show the outer surface and all other cranidial 

 features. 



Description.— GlRheWa tapered, truncated in front, strongly convex 

 transversely, with four pairs of very shallow, short furrows visible 

 in some of the specimens. Dorsal furrow deep, especially wide at the 

 sides. Occipital furrow slightly convex backward, somewhat shallower 

 medially; occipital ring expanded medially, bearing a node. Frontal 

 area vaguely divided into preglabellar field and a convex, elevated 

 border in the smaller cranidia, almost undifferentiated in the larger 

 specimens where it shows an almost uniform longitudinal convexity 

 along the midline. At the sides the frontal area has a concave longi- 

 tudinal profile determined by the steep slope in front of the ocular 

 ridges. Ocular ridges wide and strong, extended into the palpebral 

 lobes without sharp change in direction or elevation ; palpebral lobes 

 convex, elevated above the palpebral area. Distance from posterior 

 end of palpebral lobe to posterior margin somewhat shorter than 

 length of palpebral lobe. Anterior facial sutures appearing parallel in 

 dorsal view for a short distance, then gradually converging and widely 

 rounding off the anterior outline of the cranidium ; frontal portion 

 ventral-intramarginal. Surface densely covered with granules, larger 

 on the elevated portions and smaller in the depressions. Test thick. 

 Length of largest cranidium lo mm. 



Remarks. — Notwithstanding the imperfect type material, the writer 

 considers the better cranidia illustrated herein unquestionably con- 

 specific. No other known form seems referable to the genus. 



Occurrence. — The types are from a conglomerate boulder at Bic. 

 The additional specimens here illustrated were collected from boulder 

 O-i, Island of Orleans. The species is also known from Lower 

 Cambrian beds in place at Ville Guay, Quebec (Rasetti, 1945b). 



Types. — Syntypes: U.S.N.M. Nos. 65015-6. Plesiotypes: Laval 

 Univ. Nos. 3o8a-d, 309a-b; U.S.N.M. No. 123882. 



ANTAGMINAE, genus and species undetermined 

 Plate 6, figures 16-18 



Available material. — One well-preserved cranidium. 



Description. — Glabella moderately tapered, straight-sided, rounded 

 in front, fairly convex, well delimited by the dorsal furrow. Four 

 pairs of shallow glabellar furrows; occipital furrow well marked; 

 occipital ring rather long (sag.). Frontal area on the average down- 

 sloping; border convex, about twice as long (sag.) as the preglabellar 

 field on the midline. Marginal furrow almost regularly curved, medi- 



