340 Annals ov the Carnk(;if. Museum. 



broad, when entire. Fragments of specimens five or six inches long 

 are not at all uncommon. Asaplws fnargina/is has been considered 

 by some, especially the Canadian paleontologists, to be the same as 

 Asaphus canadensis Chapman, but now that we are in a position to 

 illustrate Hall's species more fully, several differences will appear. 



In the locality mentioned head and abdomen shields are common, 

 but no complete specimen nor any considerable ])ortion of the thorax 

 has yet been found. 



Descripiion. 



Cephalon broad, not very convex, with a broad concave border all 

 around. Cranidium wide in front, the fixed cheeks small and the 

 eyes close to the glabella. Glabella elongate oval, gently convex, 

 distinctly outlined. There are four pairs of shallow glabellar furrows. 

 The first two pairs are rather indistinct, broad, and are nearly perpen- 

 dicular to the axis. The third and fourth pairs are deeper, with a 

 diagonal course, and the last pair curve round at the ends, forming two 

 almost isolated lobes near the posterior edge of the glabella. The neck 

 furrow is deep and prominent on the cheeks, but is hardly visible on 

 the glabella. On the median line, opposite the anterior ends of the 

 last pair of glabellar furrows, there is a small spine. From the front 

 of the glabella a ridge runs forward across the concave border, and 

 forms a small triangular projection of the margin. It sends off a 

 a lateral ridge along the front for a short distance on each side. In 

 front of each eye is a smooth ridge which runs oblicjuely forward to 

 the glabella, meeting it at al)out the place of origin of the second 

 pair of glabellar furrows. 



The eyes are relatively small, situated far back and close to the gla- 

 bella. The free cheeks are large, the genal angles extended as broad, 

 smooth spines. A concentric furrow and ridge start just outside the 

 fixed cheeks and run forward, a little outside the base of the eye, 

 meeting the glabella ahead of the first pair of glabellar furrows. 



Surface finely granulose. 



A small cranidium, 4 mm. long, from Chazy, New York, shows that 

 in the young stages the glabella is very strongly outlined. The four 

 pairs of glabellar furrows are very distinct, and the neck segment 

 shows on the glabella, although the posterior pair of glabellar furrows 

 are so close to it as to obscure it somewhat. 



Thorax unknown. 



Pygidium strongly ribbed, moderately convex, with wide, almost 



