P. E. Raymond — Fauna of the Chazy Limestone. 381 



in front. There is a deep sulcus just in front of the middle, 

 which starts from the dorsal margin and extends half-way 

 down the valve, turning a little forward at the lower end. On 

 well-preserved specimens, in front of this sulcus there is a 

 prominent eye spot, which is sometimes translucent. Often 

 there is another slight depression or sulcus in front of the eye 

 spot. The border is wide, concave, and of nearly uniform 

 width all around from the anterior angle of the dorsal margin 

 to the posterior one. The test is frequently punctate. 



Locality. — Common all through the Chazy limestone at 

 Chazy, Valcour Island, Crown Point, and elsewhere in the 

 Champlain Valley. 



TRILOBITA. 



Heliomera subgen. nov. 



Heliomera sol (Billings). 



Cheirurus sol Billings, 1865, Paleozoic Fossils of Canada, vol. i, p. 288, 

 fig. 276. 



Cephalon short, wide, the glabella very large and flattened, 

 the cheeks small. Glabella almost semi-circular, with 3 pairs 

 of long, narrow glabellar furrows, all of which turn backward 

 on their inner ends, each joining the one back of it, and the 

 third pair joining the neck furrow, thus producing a central 

 lobe like that of Amphilichas. This central lobe is of uniform 

 width up to the inner ends of the first pair of glabellar fur- 

 rows, but turns, outward in front of that point. Toward the 

 front of this median lobe there is a slight depression, some- 

 what similar to that sometimes seen in Pliomerops canadensis. 

 The first pair of glabellar furrows run backward at an angle 

 of about 45°, the second pair at a smaller angle, while the 

 third pair are nearly parallel to the neck furrow. The glabel- 

 lar lobes are narrow and club-shaped. This radiating arrange- 

 ment of the glabellar furrows and lobes probably suggested 

 the specific name. The neck ring is wide, flat, and separated 

 from the glabella by a deep furrow, which extends the whole 

 width of the cephalon. The cheeks are not sufficiently well 

 preserved to be described, but enough of the test remains to 

 show that the outline of the cephalon was the same as in 

 Pseudosphcerexochus vulcanus. There is a narrow smooth 

 border all around the front of the cephalon, and the surface is 

 covered with fine tubercles. The relations of this species are 

 rather doubtful. From the form of the cephalon it evidently 

 belongs close to Pseudosphwrexochus, but there has not been 

 seen in species of that genus any tendency to vary in the 

 direction of an isolated central lobe and long isolated glabellar 



