Silurian Fossils of Canada, 63 



Several specimens of tlie pygidium of this rare species and one 

 individual nearly entire but flattened by pressure have been found 

 at Ottawa and are now in the collection of the Survey. I am 

 indebted to Col. Jewett, of Albany, for the loan of the specimen 

 figured. It is more perfect than any of ours. 



Locality and formation. — City of Ottawa, Trenton limestone. 

 Occurs also in the State of New York in the same Rock. 



Collector. — E. Billings. 



Dalmanites Achates. N. s. 



Fig. 9. — Dalmanites Achates^ 



Description. — Elongate-oval, posterior angles of head produced 

 into short spines, proportional length of head thorax and pygi- 

 dium apparently 5, YJ-, 5, total length about one inch and a half. 



Head, excluding the spines, very nearly a perfect semi- circle, 

 ■with a shallow concave marginal groove all round the front and 

 sides, and a strongly defined neck-furrow extending across at less 

 than one line from the posterior margin ; glabella equal to the 

 whole length of the head, moderately convex in front, the anterior 

 lobe transversely oval, twice the width of the neck-segment, not 

 defined at the sides in front, but confluent with the surface of the 

 cheeks. The anterior furrows have their inner extremities separated 

 by a space equal to their own length, extending obliquely out- 

 wards to points situated a little forward of the inner front angles 

 of the eyes. The middle furrows have their outer extremities 

 opposite the mid-length of the eyes and extend inward in a direc- 

 tion gently inclined forward until their inner extremities are a 

 little within one third the width of the glabella at mid-length 

 from each other. The third furrows are opposite the posterior 

 angles of the eyes, parallel or nearly so with the middle pair and 

 about the same length. The neck furrow is well defined quite 



