76 



Annals of the Carnegie Museum. 



a new subgenus with Ampliion canadensis as the type.^" Aviphion pseiido- 

 articulatiis Portlock, A. benevolens Salter , A. senilis Ba.rra.nde, and possibly 

 A. westoni^BiWings, A. nevadensis Walcott, and A. harrendei Billings, 



6 7 8 



Fig. 6. Pliomerops canadensis (Billings). Copy of Billings' figure, twice 

 natural size. On the specimen, which is now before the writer, the median furrow 

 is so faint that it can hardly be seen. It is not present on mature specimens. 

 Fig. 7. Pliomerops barrandei (Billings). Copy of Billings' figure. 

 Fig. 8. Pliomerops senilis (JidLvrd^nAe). After Barrande. 



belong to this subgenus. This last species has a peculiar glabella, the 

 median furrow showing on the cast and the first lateral furrows being 

 represented by pits. 



Genus Ceraurus Green. 



Subgenus Nieszkowskia Schmidt. 



Nieszowskia sp. ind. 



Plate XVIII, figure 13; Plate XIX, figure 20. 

 A single pygidium which probably belongs to one of the described species 

 of this genus has been found at Chazy. The axial lobe shows two narrow 

 convex rings which extend across its full width, and back of them a ring 

 which has so fused with the terminal triangular segment as to produce a 

 circular ridge. Within the circle so formed is the remnant of another 

 segment, forming a small hemispheric mound. The pleura consist of two 

 pairs of segments with free terminations. 



Locality. — McCullough's sugar-bush, Chazy, New York. No cranidia 

 of Nieszkowskia have yet been found at this locality. 



^"American Journal of Science, Series 4, XIX, 1905, 377. In designating 

 A. canadensis as the type it is to be understood that the species described under 

 that name in my paper of 1905 is meant. Billings figured and described as the type 

 of this species a small specimen with a furrow in the front of the glabella. This is 

 an immature individual, retaining this during the early stages of the ontogeny 

 only. 



