210 THE CANADIAN NATURALIST. [Vol. vi. 



eastward, and apparently at about the same angle. The best ex- 

 posures of these rocks in this vicinity occur opposite the central 

 portion of the city, where they are brought to view in a number 

 of abrupt, quickly concealed ridges. These ridges trend northerly 

 and southerly, and appear to be all constructed upon the same 

 pattern, having on the west a steep, on the east a more gradual 

 slope. Only the western faces are naturally exposed. This 

 uniformity of structure is very striking, and there are reasons for 

 believing that it has resulted largely from successive short, sharp 

 folds in the strata, of which we have a fine example in the rocks 

 east of Lansingburgh ; but as nearly the whole district is covered 

 with a thick sheet of drift, and the rocks bear evidence of exten- 

 sive faulting, much further study will be necessary before it will 

 be fully understood. 



These ridges generally consist for the most part of coarse red 

 and yellow weathering slates and shales, with occasional thin-bed- 

 ded sandstones ; but the most of them are supposed, and four of 

 them are known, to hold subordinate limestone deposits. Of these 

 deposits the two westernmost individually consist of a few courses 

 of thick-bedded limestone, and of irregular, sometimes lenticular, 

 sp:irry and frequently pebbly masses, varying from one to several 

 hundred pounds in weight, imbedded in a coarse, dirty-looking 

 arenaceous matrix : while the others form tolerably compact, 

 even-bedded limestones, with an abundance of scattered black 

 nodules, from twenty-five to thirty feet in thickness. 



So fir as investigated, these limestones have been found to be 

 highly fossiliferous, though the fossils are usually in a very 

 fragmentary condition. From two of them — one of the conglomer- 

 ates and one of the even-bedded masses — the writer has made 

 frequent collections during the last three years. With a single 

 exception the same species occur in both. Up to the present 

 time they have yielded eighteen species, which are distributed as 

 follows : 



Protozoa (^AnJiencijathus) 1 species. 



Brachiopoda 7 " 



Lamellibranchiata 1 " 



Gasteropoda 1 



Pteropoda [Jli/olifhes) 2 



Annelida {Salterelht) 1 



it 



a 



Crustacea 5 



(t 



Total, 18 



