104 THE CANADIAN NATURALIST. [Vol. ix. 



or ectognath before us, with rounded scaly basal part and narrow 

 maxillary process with about 12 denticles and 3^ inches in length. 

 is sufficient to indicate the existence of a new and large species, 

 which may for the present be named F. Canadensis^ and which 

 was a Canadian predecessor of P. Anglicus.^' 



Since the above was written the removal of a part of the stone 

 has exposed a little more of the mandibular edge, so as to show 

 a few more teeth, making about fifteen in all, which are of the 

 form represented in Fig. 1. c, except the posterior one. which is 

 broad and slightly notched in front. 



Lieut. -Col. Grant has more recently obtained another fragment 

 of an animal apparently of the same species. It seems to be a 

 segment of the thorax, somewhat crushed at the ends, but show- 

 ing the characteristic markings very distinctly at the anterior 

 edse. The portion preserved is barely six inches in length, and 

 an inch and a half wide. Fig. 2 represents the middle portion 

 of it. 





fci^tti 



Fig, 2. Body ring of the same, central portion, natural size. 



The first-mentioned specimen was found by its discoverer in 

 the corporation quarry at Hamilton, in the lower cherty beds of 

 the Niagara limestone, which at this place contains also a large 

 Conularia and species of Graptolites. The second specimen 

 was found at some distance from the first, but apparently in beds 

 of the same age. The specimens are sufficient to indicate the 

 existence of a very large crustacean of this genus, apparently the 

 first found in the Niao-ara limestone formation of Canada. 



According to the Kev. Mr. Symonds, in Woodward's Monograph 

 of the British Merostomata,* the oldest known Fterygotus in 



* Publications of Pal^ontographical Society, Vol. XXV. 



