Mesozoic and Ccenozoi'c Geology and Palaeontology. 95 



L. multiradiata^ Anomia vancoicverensis, Ostrea idriaensis,0. aj^j^ressa, 

 Bhynchonella ivhifneyi^ Smilofrochus curtus. 



And from the Sierra de las Conchas, near Arivechi, Sonora, Mexico, 

 Fusus mexi'canus, Euspira tabulata, Chemnitzia zebra^ Tylostoma 

 mutabile, Anchiira monilifera, Cerithium mexicanum, Angaria cin- 

 gulata, Cinulia rectilabrum, Plioladomya sonorensis, Cardiitm 

 sabulosum, C g^^anuUfeinim, Cardita alticosta, Remondia furcata, 

 Cucullcea mei^mis, Gryphoia mucronata. 



Prof. E. D. Cope* described, from Raritau bay, Ornithotarsus im- 

 manis; from Western Kansas, llacrosam^us proriger, now Liodon 

 proriger ; from Sampson county. North Carolina, Hypsibema crassi- 

 cauda, Hadrosaitrus tripos, and Polydectes biturgidus; from New 

 Jersey,f Ilosasaurus maxlmus^ and from Alabama, Clidastes propytlion. 



Prof. O. C. MarshJ described, from the greensand marl, nearHorners- 

 town, Monmouth county. New Jersey, Mosasauriis copeanus^ 31. 

 miersi, 31. princeps^Halisaiirusfraternus^ now Baptosaurus fraternus, 

 and H. platyspondylus, now B. platyspondylus. 



Prof. Leo Lesquereux§ described, from the Dakota Group, at Fort 

 Ellsworth, Nebraska, Populites microphyllus, Phyllites betuloifolius, 

 Per sea nebrascensis, now LaurUs nebrascensis, and Sassafras leconte- 

 anum^ now Persea leconteana. 



The Cretaceous is the lowest formation exposed inLouisiana,|| audit 

 comes to the surface only at the limestone hills of St. Landry and 

 Winnfield. The borings that have been made for salt, however, show 

 that it is more that 1,000 feet in thickness. The strata are saline, and 

 pure beds of rock salt sometimes occur. 



The Cretaceous rocks have been observed in Plymouth, Woodbur3\ 

 Cass, Guthrie, Pottawattamie, Montgomery, Carroll and Greene coun- 

 ties,^ Iowa. In all but the first two the}' appear as outliers. On 

 account of the drift which covers the western half of this State, the 

 area of the Cretaceous has not been determined. The exposure in Ply- 

 mouth and Woodbury counties extends into Dakota, and belongs to 

 the Dakota Group. The maximum thickness as far as observed is 350 

 feet. The rocks rest uuconformabh^ upon the coal measures beneath, 

 and have a northwesterly dip, while the palaeozoic strata dip south- 

 westerly. 



* Proc. Amer. Phil. Soc. 



t Proc. Bost. Soc. Nat. Hist. 



X Am. Jour. Sci. and Arts, 2d ser., vol. 48. 



I Trans. Am. Phil. Soc, vol. 13. 



II Geo. of Lou., 1870. 



1[ Geo. Sur. Iowa, 1870. 



