Mesozoic and Coinozoic Geology and Paloiontology. 81 



estimated at from SO to 100 feet, underlaid by No. 2 of the Niobrara 

 division. The entire surface of the country, from the latter place, in 

 Qortheastei'u Dakota, to Fort Dakota, at Sioux»falls, on the Big Sioux 

 river, is referred to the Cretaceous. 



Prof. E. D. Cope* described, from Camden county. New Jerse}^ Sv- 

 clastes platyops,a,nd Thoracosaui'us brev isp i tius,now Holops hrevispinus. 



The Cretaceous rocks occupy a belt or strip of country in New Jer- 

 seyf which stretches obliquely across the State, from Raritan \)a.y on 

 the northeast, to the head of Delaware bay on the southwest. The 

 extreme length of the formation, from the highlands of Navesink to 

 the Delawai'e, above Salem, is about 100 miles. Its breadth at the 

 northeast end, from Woodbridge to Deal, is 27 miles, and at the south- 

 west end, from the mouth of Oldman's creek to Woodstown, it is 

 lOf miles. The area included in this formation is about 1,500 square 

 miles. 



It is subdivided in ascending order, as follows: 



1. Plastic clays, 210 feet. 



2. Clay marls, 277 feet. 



3. Lower marl bed, 30 feet. 



4. Red sand, 100 feet. 



• 5. Middle marl bed, 45 feet. 



6. Yellow sand, 43 feet. 



Total thickness, 705 feet. 



The kaolin, which is dug so extensively, belongs to the plastic cla}' 

 of the above subdivision. It is a very fine micaceous sand, with some 

 fire-clay intermixed, and streaks of clay passing through it. It is of 

 a bluish-white color, sandy in consistency when drained, but past}" 

 when worked up in water. 



Prof E. D. Cope]; described, from New Jersey, Osteopycjis emargin- 

 atus^ CUdastes iguanavus, Nectoportheus validus, Emys petrosus, 

 now Agomphus petrosics, Elasmosaurus orientalis, and from the 

 Niobrara Group, near the boundary line between Kansas and Colo- 

 rado, a short distance north of the Smoky Hill fork of the Kansas 

 river, E. i^latyurus. 



Dr. Joseph Leidy described, from near Fort Hays, Kansas, Ptychodus 

 occidentalism and from the Judith River wroup, Auhlysodon mirandiis^ 

 now Aiiblysodon horridus. 



'■■ Proc. Acad. Nat. Sci. 



t tteo. of New Jersey. 1868., 



t Proc. Acad. Nat. Sci. 



