No. 2.] 



DAWSON — A CANADIAN PTERYGOTUS. 



103 



A CANADIAN PTERYGOTUS. 



(^Pterygotus Canadensis.') 



Among some specimens kindly presented to the museum of 

 the University in the winter of 1877-8, by Lieut. -Col. Grant of 

 Hamilton, was a slab of Niagara limestone holding a well-pre- 

 served ectognath or mandible of a large Pterygotus. (Fig. 1.) 



Fig. 1. Ectognath of Pterygotus Canadenftif, natural size. (The shaded 

 portions represent the slaty character of the surface.) 



c. teeth enlarged. 



As the species seemed to be new, and I could not learn that 

 anything similar had been found in rocks of this age in Canada, 

 a notice of it was communicated to the Natural History Society 

 of Montreal at its meeting of April 28, 1879, and was reported 

 as follows in the Daily Witness of the 30th : 



" A very remarkable discovery recently made in the Niagara 

 limestone is that of some fragments of a gigantic Crustacean of 

 the genus Pterygotus, comparable in size with the great Pterygotus 

 Anglicus of the Devonian of Scotland, though of much greater 

 geological age. Some small species of Pterygotus have been de- 

 scribed by Hall from the Waterlime formation of New York, and 

 a fragment of an undescribed species has been found by the same 

 palaeontologist in the Clinton ; but the present is, so far as known, 

 the first example of a large and well-developed species of this 

 genus from so old a formation. Col. Grant hopes to obtain ad- 

 ditional remains. In the meantime the well-preserved maxilliped 



