42 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 98 



are narrow and the brim practically wanting across the front of the 

 glabella. The libragene has a rather wide ocular platform and is not 

 very convex. A heavy, thickened border extends into a long genal 

 spine. The associated pygidium is well fused, although three pleural 

 furrows are still visible. The margin is nearly even with faintly 

 defined waves to represent the marginal spines. Surface granulose 

 on the highest points and toward the margins marked by heavy 

 irregular lines. 



Locality 54s. 



Holotypc and paratypes. — U.S.N.M. Nos. 98522a-d. 



PTARMIGANIA, sp. undet. 

 Plate 3, fig. 34 

 A minute cranidium, the characters of which are well shown by the 

 illustration, does not fit the recognized species. It may well repre- 

 sent a young stage, but if so the species to which it belongs is not 

 determinable, since there is no ornamentation to assist. 

 Locality 54s. 

 Figured specimen. — U.S.N.M. No. 98523. 



GLOSSOPLEURA Poulsen, 1927 

 GLOSSOPLEURA PRONA, n. sp. 



Plate 8, figs. 11-14 



This species is characterized by its smoothness and the flatness of 

 the pygidium. The eyes are large, and the glabella expands only 

 slightly anterior to the forward end of the eyes. 



The pygidium is flat, with a faint dorsal furrow. Pleural furrows 

 are faintly visible between the axis and the wide flat border. 



This species is similar to G. biou but the pygidium is flatter and the 

 cranidium has less brim. 



Localities 55P, 55q. 



Holotypc and paratype. — U.S.N.M. Nos. 98524a, b. 



GLOSSOPLEURA ARRECTA, n. sp. 



Plate 8, figs. 8-10 



This species is associated with G. promt but contrasts strongly with 

 it because the pygidium is highly arched. This arching is rather even 

 so that the dorsal furrow becomes shallow. Longitudinally the axis 

 is arched, the declivity at the rear being very steep. Pleural grooves 

 are practically absent. 



Localities 55P, 55q. 



Holotype and paratype. — U.S.N.M. Nos. 98525a, b. 



