NO. 22 CAMBRIAN TRILOBITES, 3D CONTRIBUTION RESSER 23 



Diagnosis. — Small trilobites. Glabella long, rather slender, gently 

 tapered, rounded in front. Glabellar furrows faintly indicated. Neck 

 furrow deep and neck ring expanded into short, blunt spine. Facial 

 suture converges slightly anterior to the eyes, but back of them 

 diverges rapidly to form very large posterolateral limbs. Eyes small, 

 situated close to the anterior end of glabella. Eye lines rather strong, 

 with a horizontal course. Brim with a narrow preglabellar area, and 

 thickened, somewhat upturned rim. 



Compared with Plagiura the new genus had deeper furrows through- 

 out, and also has a raised rim. 



Range. — Lower Cambrian, Cordilieran and Appalachian regions. 



Genotype. — Ptyclioparia f cleadas Walcott. 



Plagiurella cleadas (Walcott) 



Ptychoparia .' rlcadcu WAi.corr, Sniitlisoiiian Misc. Coll., vol. 67, no. 3, p. 83, 

 pi. 12, fig. 2, 1917. 



Lower Cambrian, Mount Whyte; (loc. 57s) Mount Bosworth, 

 Alberta, 



Holotype.— U.S.N. M. no. 64382. 



POULSENIA Resser, 1936 



Poulsenia cossus (Walcott) 



Ptychoparia cossus Walcott, Smithsonian Misc. Coll., vol. 67, no. 3, p. 86, 

 pi. II, figs. 5, Sa, 1917- 



Lower Cambrian, Mount Whyte; (loc. 6ia) Yoho Canyon, British 

 Columbia. 



Holotype. — U.S.N. M. no. 64370. 



Poulsenia crassilimbata (Poulsen) 



Ehathia ? crassilimbata Poulsen, Meddels. Gr^nland, vol. 70, p. 274, pi. 17, 

 figs. 5, 6, 1927. 



Middle Cambrian, Cape Wood; Cape Frederick VII, northwest 

 Greenland. 



Holotype. — Min. Mus. Copenhagen. 



PROZACANTHOIDES, n. gen. 



Diagnosis.— GlaheW^ large, occupying the major portion of the 

 cranidial length, rectangular in shai^e, with a tendency to expand for- 

 ward. Three pairs short glabellar furrows, the anterior pair very faint 

 and the rear pair sharply reflexed. Occipital furrow straight and 

 clearly impressed ; occipital spine present. Fixed cheeks confined to 

 the large palpebral lobes and small lobes anterior to the eyes. Facial 



