119 



are both built on this formation. To the north of Aylmer, overlying 

 the sandstones, whose thickness is evidently not far from 100 feet, ai'e 

 to be found beds of a transitional nature. They are only a few feet 

 thick, very dark in colour, brittle in texture, and apparently unfos- 

 siliferous, with innumerable joints and cleavage planes running in all 

 directions. These are immediately followed by beds of compact greyish 

 limestone holding orthoceratites in abundance, four or five feet above 

 which other beds hold in great profusion the well known Stromato- 

 cerium rugosum, Hall — a sponge or sponge-like organism. Regular 

 colonies of these fossils are to be seen occupying considerable patches in 

 the fields on the north concession i-oad. These beds have a very slight 

 inclination to the north, with an almost due east and west strike. Follow- 

 ing these measures at right angles to the strike numerous Chazy fossils 

 were collected. Thac very characteristic band of impure friable lime- 

 stone holding abundance of Leperditice was found. (See Decade III, 

 Geol. Surv. Can., page 92.) Then following in a north-easterly 

 direction, at some 2| miles from Aylmer, numerous species of fossils 

 characteristic of the Black River formation fauna were obtained. Much 

 work still remains to be done in this neighbourhood, as the rocks are 

 highly fossiliferous and the specimens in many instances very well pre- 

 served. Nineteen species of fossils were collected from these beds. 

 Much credit falls to Mr. E. T. W. Sowter for the work he has already 

 accomplished in these interesting exposures. 



Trenton Formation. — The very numerous and highly fossiliferous 

 exposures of this formation about Ottawa, from which the late Mr. E. 

 Billings, the late Dr. Van Cortlandt, and many members of the Field 

 Naturalists' Club obtained a splendid series of fossils — a typical col- 

 lection of which is to be found in the Museum of the Geological and 

 Natural History Survey— proves still a rich hunting ground for the 

 palaeontologist. 



During the past season a fine exposure was observed within the 

 Rideau Hall grounds, where an interesting collection of fossils was 

 made, amongst which were locrmus suhcrassus, Meek and Worthen ; 

 Lichenocrinm crater I for mis, Hall ; a Disciiia like D. Circe, Billings ; 

 and about twenty additional species characteristic of Trenton age. 



