468 Fossils of the Chazy Limestone, 



Head convex, semicircular, or rather crescentiform, the posterior 

 angles being produced backwards ; glabella sub-cylindrical, 

 rounded, and abruptly elevated in front, the sides nearly parallel, 

 crossed by a narrow, rather deep neck-furrow near the posteiior 

 margin ; two indistinct oblique lateral furrows. On a side view, 

 the outline is nearly straight, or scarcely at all convex from the 

 posterior margin to near the front, when it descends with an 

 abrupt curve to the edge of the narrow marginal furrow which 

 runs round the whole of the head, close to the edge. 



Fig. 36, 37, 38. 



Fio\ 36. — Two specimens of the glabella of a small trilobite from the 

 Chazy Limestone ; genus not determined. 



37. — Fragment of Bathyrus Angelini. 



38. — Harpes antiquatus. 



The eyes as indicated by the course of the facial suture, are 

 large, crescentiform, and a little more than one-third the whole 

 length of the head. The anterior angles of the eyes appear to 

 be a little in advance of a line drawn across the glabella at half 

 its leno-th, while the posterior angles are a little in advance of the 

 neck-furrow. 



The thorax is not well known. From several fragments of it 

 the central lobe appears to be cylindrical, strongly convex, a little 

 wider at the anterior than at the posterior extremity. 



The pygidium is strongly convex, and closely resembles that of 

 B. extans. 



Allied to B. extans (Hall, sp.), but that species has the poste- 

 rior spines of the glabella of great length, extending backwards 

 to the pygidium. 



Dedicated to M. P. Angelin, the eminent Swedish Palaeonto- 

 logist. 



Locality and Formation. — Grenville ; Chazy limestone, Gren- 

 ville and Fitzroy Harbour. 



Collectors. — J. Richardson, Sir W. E. Logan. 



