COPE ON GEOLOGY AND VEETEBRATE FOSSILS. 571 



ness), from the summit of which I obtained a sacrum and various other 

 vertebrae and fragments of limbs of Binosauria, with an ilium of the 

 form of that of Eadrosaurus. There is no interruption in this bed, the 

 occasional thin layers of sandstone existing in a few localities, being of 

 far less importance than those found in No. 6 at various horizons. 



Where the beds display their greatest thickness, the shell-bearing 

 sandstone above described reaches a depth of 50 to GO feet, containing 

 immense numbers of Molluscs in good preservation. In fact, this bed 

 contains the species of the formation, excepting the Ostrea subtrigonalis, 

 which occurs higher in the series ; some of the Uniones also are found at 

 "other horizons. The species as identified by Messrs. Meek and White 

 are the following: 



Physa. 



Physa copei White. 



Viviparus leidyi yar.formosus M. & H. 



Viviparus ( Campeloma) vetuhis M. & H. 



Sphcerium subellipticum M. & H. 



Cyrena cytheriformis M. & H. 



Anodonta. 



Unio. 



Unio. 



Unio. 



Unio. 



Unio danai M. So H. 



Above the sandstone are soft arenaceous and clayey beds, of vary- 

 ing extent, which amount at one point on Dog Creek to 30 feet in thick- 

 ness. They are often striped with red, and are less fossiliferous than 

 the strata below them, but contain a larger quantity of petrified wood. 

 Large logs are ft-equently seen projecting from the fayades of this bed. 

 At a point on Dog Creek, 20 miles from its mouth, this bed is about 

 50 feet in thickness, and is overlaid by a layer of rusty sandstone 

 of 15 feet. Above this is a repetition of the arenaceous marl of 20 

 feet, on which a reddish shale of 10 feet reposes. This stratum sup- 

 ports a bed of black impure lignite of 5 feet depth, which is followed 

 in the ascending order by 7 feet of shale, 2^ feet of lignite, a foot of 

 black shale, and a bed of densely packed Oysters, of the species Os- 

 trea subtrigonalis, of about 15 feet in thickness. At other localities to 

 the north and east of this one, the bed of Ostrea was observed over- 

 lying the lignite ; but at others, once on Dog Creek and once near Cow 

 Island, tliese shells were found in the soft sandstone at the summit of 

 the bluffs, without any lignite being visible beneath. This bed of Ostrea 

 subtriyonaUs is the summit of the series observed by me in this region, 

 and it stands at the top of the section given by Dr. Hayden in the 

 memoir already quoted.* 



* Transactions of the American Philosophical Society, 1860, p. 129. 



