NO. 22 CAMBRIAN TRILOBITES, 3D CONTRIBUTION — RESSER I9 



METISIA, n. gen. 



Many heads and tails and several cheeks were recovered from a 

 small limestone boulder at Metis, Quebec. All belong to a single 

 species, which resembles forms younger than Lower Cambrian. Some 

 doubt regarding age remains in all such cases where a fauna is lacking 

 to verify the horizon to which the boulder originally belonged. 



Diagnosis. — Cranidium simple, highly arched. Glabella large, occu- 

 pying fully half of the cranidium ; dorsal furrow strong ; glabella 

 tapered, rounded in front. Glabellar furrows faintly indicated. Oc- 

 cipital furrow deep; neck ring only slightly swollen in the middle. 

 Fixigenes narrow, arched transversely. No eye lines. Eye lobes 

 moderate in size. Brim confined to a swollen rim. Anterior and 

 dorsal furrows join. Facial suture slightly divergent anterior to the 

 eyes ; intramarginal for some distance. Anterior angles turned down 

 for a considerable distance. 



Libragenes of normal shape and convexity. Rim heavy, widening 

 somewhat at the genal angle. Length of genal spine unknown. 



Pygidium with a high, long, and wide axis. About three segments 

 shown in axis and on pleural lobes. Pleura well fused ; three pleural 

 furrows clearly defined. 



Surface granulose. 



Genotype.— Ptychoparia metisensis Walcott. 



Metisia metisensis (Walcott) 

 Ptychoparia metisensis Walcott, loth Ann. Rep. U. S. Geol. Surv., p. 651, 

 text figs. 68a-d, 1891. 



Lower Cambrian, boulder in conglomerate ; Metis, Quebec. 

 Cotypes.—U.S.'^.'M. no. 23838. 



MONOCHEILUS, n. gen. 



Diagnosis.— ^^wvaW trilobitcs with large glabella. Glabella occupies 

 most of head, rounded in front, without glabellar furrows. Brim 

 consists of a single flat, tongue-shaped projection, only as wide as 

 the glabella. Fixigenes lacking. Eyes large ; the palpebral lobe arising 

 directly from the dorsal furrow. Posterolateral limbs narrow. 



This genus is similar to Bayfieldia Clark differing in the lack of 

 fixigenes and in its much larger eyes. 



Genotype. — Conocephalites anatinus Hall. 



Name. — /xoi'as = single ; x^Aos^brim. 



