80 Cretaceous. 



of the Las Uvas Canon, the Cretaceous belt is over a mile wide, and 

 forms hills about 1,000 feet above the plain. 



The base of the foot hills of the Sierra Nevada is bordered, for a large 

 part of the distance, between Tejon Pass and the head of the Sacra- 

 mento Valley, by a series of beds of stratified Cretaceous materials- 

 resting appai'ently undisturbed, and in a nearl}^ horizontal position, on 

 the upturned edges of the metamorphic slates and granitic rocks of 

 which the foot-hills are formed. These materials, however, are not 

 seen farther south than Folsom. Good exposures may be seen on Butte 

 and Chico creeks. On the north side of the Cottonwood, beginning at 

 Horsetown, and extending west to the Coast Ranges, Cretaceous strata 

 lie at the base of the mountains, and form a table-land about 1,200 feet 

 high, and have generally a southeasterl}' dip. Cottonwood creek runs 

 nearly south from the summit of the Siski^^oii Mountains to the 

 Klamath river, a distance of 13 miles. The vallej' of which is about 

 10 miles long, and is excavated in the softer and unaltered Cretaceous 

 strata, having on either side harder rocks, namely the auriferous slates 

 on the west, and the modern volcanic on* the east. 



Dr. Joseph Leidy* described, from New Jersey, Crocodilus tene- 

 brosus, C. obscurus, now Holops obscurus, Gcelosaurus antiquus, 

 Tomodon horrijicus, now Diplotomodonn horrijicus, Chelone sopita^ 

 now Osteopygis sopitus, Emys flrmus, now Agomplius Jirmus, E. beatus, 

 now Adocus beatvs, and BotJvemys cooki ; from Maryland, Astrodon 

 johnstoni ; and from Minnesota, Piratosaurus plicatus. 



T. A. Conrad,f from New Jersey, Ostrea tuonieyi^ Mortonia turgida, 

 and Volutilithes lioderma, now Leioderma lioderma. 



In 1866, T. A. Conrad;]; described, from Alabama, Diploschiza cre- 

 tacea^ and Terebratulina Jilosa. 



Prof. .E. D. Cope§ described, from the greensand two miles south of 

 Baruesboro, Gloucester count}'. New Jersey, Lcalaps aquilunguis, and 

 from Camden county, Aturia paucij'ex. 



In 1867, Prof F. V. Haydenl referred the rocks at Yankton, the 

 capital of Dakota Territory, located on the Missouri, about twelve 

 miles above the mouth of the James, to the yellow, calcareous 

 marl beds of No. 3, of the Niobrara division of the Cretaceous. The 

 same rocks were found at Fort James, about twelve miles below the 

 mouth of Firesteel creek, a branch of the James, and their thickness 



'■■' Cret. Reptiles, U. S.. vol. 14, Smithsonian Contributions, 

 t Proc. Acad. Nat. Sci. 

 J Am. Jour. Conch., vol. 2. 



I Proc. Acad. Nat. Sci. 



II Am. Jour. Sci. and Arts, 2d ser., vol.43. 



