271 



off. Prof. Hall's fig. 18, above cited, shows a portion of the anterior half 

 of a hypostoma with the same rounded front margin that is seen in our 

 specimens. The two small muscular pits are well preserved in one of our 

 specimens, but they are scarcely visible in the one figured. 



It may be here remarked that in the Chazy limestone a perfect hypos- 

 toma, quite different from the above, has been found, showing that in that 

 formation there are at least two species of Asaplms. 



Locality and Formation. — Port aux Choix, Point Rich, Table Head, 

 and Bonne Bay, Newfoundland, — F, to M, inclusive ; Quebec group. 



Collector. — J. Richardson. 



ASAPHUS HUTTONI. (N. Sp.) 



Fig. 256. 



Fig. 257. 



Fig. 258. 



Fig. 256. — isaphus Huttoni. Fig. 257. — A. Morrisii. Fig. 258. — .^. quadraticaudatus. 



Description. — Pygidiura semi-ovate moderately convex, length a little 

 greater than half the width. Axis narrow, convex, well defined, one- 

 fifth the whole width at the anterior margin, tapering to one-half at the 

 apex ; the front half with about eight very obscure ribs ; the posterior half 

 apparently smooth. Side lobes, with about eight obscure ribs in the 

 anterior two-thirds, which die out at one-third the width of each lobe from 

 the margin ; the posterior third on each side of the apex of the axis smooth. 

 There is a smooth border all round which is gently concave on approach- 

 ing the margin. The border is one-sixth the whole width. The anterior 

 margin is straight for the middle third ; the outer third on each side is 

 gently convex and facetted. 



Resembles A. Morrisii, but is more numerously ribbed. It is more 

 nearly allied to A. Canadensis (Chapman), of the Utica slate, but that 

 species is more strongly and distinctly ribbed. 



Length of the specimen, 5 hues; width, 7 lines. 



Locality and Formation. — N, Table Head, Newfoundland ; Quebec 

 group. 



Collector. — J. Richardson. 



