1911] The Ottawa Naturalist. 197 



followed by beds of blue-black limestone, dove limestone, and 

 gray magnesian limestone. The upper portion of the forma- 

 tion is said to lack the black limestone and to consist of 

 alternations of dove limestone and gray magnesian limestone, 

 light gray to white thin-bedded, impure limestone, and yellow 

 water-lime. It will be noted that this succession is very similar 

 to that shown in the sections presented above. The fauna 

 has not yet been described, but it is said to contain numerous 

 small ostracods, an undescribed Bathyuriis, gastropods, cephalo- 

 pods, and several species of Tetradium. 



Summary. 



The sections in the vicinity of Ottawa show about 250 feet 

 of strata between the Beekmantown and the base of the Black 

 River. These strata are characterized by two groups of species. 

 The lower 125 to 135 feet contain a small fauna, some of whose 

 species are found in the upper part of the Chazy formation of the 

 Champlain Valley, and this portion is undoubtedly to be cor- 

 related with the Upper Chazy, or at least with the tipper Chazy 

 as exhibited north and west of Montreal. The writer some years 

 ago suggested the name Aylmer* formation for the Chazy of the 

 Ottawa Valley, and it will probably be well to restrict this term 

 to the beds characterized by the Chazy fossils, and use it as the 

 local designation of these lower beds. 



The upper portion of the section consists of 115 to 125 feet 

 of limestone, sandstone and shale, with fossils more nearly akin 

 to those found in the Black River and lacking the typical Chazy 

 species. The fauna of these beds is very imperfectly known, and, 

 owing to the poor state of preservation of the specimens at most 

 localities, its elucidation will require a considerable amount of 

 field work and study. This portion of the section, while united 

 by several species which range throughout the whole thickness, 

 is capable of subdivision into two members, the lower of which 

 contains most of the shale and sandstone, and the upper the pure 

 limestone. The lower portion contains an immense number of 

 small ostracods, and, in the middle, great numbers of gastropods 

 and other fossils. This member is from 65 to 75 feet in thickness. 



The upper member is composed mostly of pure limestone, 

 has a larger fauna than either of the other formations, the upper 

 15 feet being especially fossiliferous. This is the Lowville of the 

 New York section and the thickness is about 50 feet. 



*Annals Carnegie Museum, Vol. Ill, p. 380, 1905. 



