254 bulletin: museum of comparative zoology. 



green, yellow, and brown sandy and calcareous shale, and in sand- 

 stone in the Lorraine (Pulaski). 



When the Trenton is traced northward from Trenton Falls it is 

 found well exposed along the tributaries entering the Black River 

 from the west. In this region the Cryptolithus bed is no longer seen 

 at the base of the formation, but the middle beds with Prasopora 

 simulatrix are the same as at Trenton Falls. At the top, however, a 

 considerable thickness of strata are added, of a kind not seen at 

 Trenton Falls, and containing a fauna not found there. Above thin- 

 bedded limestone containing Rafinisquina deltoidea, these beds being 

 the equivalent of the upper strata at Trenton Falls, one finds thick- 

 bedded impure dark gray limestone which on weathering breaks down 

 into a rubbly mass. This limestone contains many gastropods and 

 some other fossils, the most characteristic being Hormotovia trentonen- 

 sis, Fusispira s ubf us i form is, 'and Cyclospira bisulcata. 



It is interesting to note that the species which are most characteristic 

 of the upper beds and most of which are not found at Trenton Falls, 

 were described originally from this region. Thus the type-localities 

 of Fusispira subfusiformis are Adams, Jefferson County, where only 

 these upper beds are exposed, and Turin, Lewis County. Trocho- 

 ncma ambigua, Fusispira vittata, and Cyclospira bisulcata were all 

 described from specimens obtained at Adams, and Holopea paludini- 

 formis and Subulites elongatus were both found originally in the higher 

 Trenton strata at Watertown. Of all these species, only the last has 

 been found at Trenton Falls, and in New York they are characteristic 

 of strata above the strata exposed at Trenton Falls, and the highest 

 Trenton limestone exposed in the State. 



Ontario. 



Crossing into Ontario, the section is practically identical with that 

 in northern New York, except for certain local developments. The 

 strata in the middle of the Trenton remain the same as those at Tren- 

 ton Falls, but the lower beds do not carry Cryptolithus. The lower 

 beds do, however, show a decided recurrence of Black River conditions 

 and faunas, as high as 100 feet above the base of the formation, so that 

 there is here practically continuous sedimentation after the Leray, the 

 Trenton fauna gradually replacing the Leray fauna. In this respect 

 the section reminds one greatly of Kentucky, as will be seen later. 



The section, in descending order, is as follows, the section at Ottawa, 

 being taken as typical of the region. 



