Mesozoic and Cainozoic Geology and Paloiontology. 85 



L. multiradiata, Anomta vancouverensis, Ostrea idriaensis,0. appressa, 

 Rhynchonella lohitneyi^ SmilotrocJius curtus. 



And from the Sierra cle las Couchas, near Arivechi, Sonora, Mexico. 

 Fusus mexicamis, Euspira tahulata, Chemnitzia zebra, Tylostoma 

 mutahile, Anchura monilifera, Cerithium mexicanum, Angaria cin- 

 gulata, Cinulia rectilabrum, Pholadomya sonorensis, Cardium 

 sabulosum, C granuUferum, Gardita alticosta, Bemondia ficrcata, 

 Cuculloia inermis, Gryphaia mucronata. 



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

 manis; from Western Kansas, Macrosaurus proriger, now Liodon 

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

 cauda, Hadrosaurus tripos, and Polydectes biturgidus; from New 

 Jersey,! ^osasaurus maximtcs, and from Alabama, Clidastes propython. 



Prof O. C. Marsh+ described, from the greensand marl, near Horners- 

 town, Monmouth count\^, New Jersey, Mosasaurus copeanus, M. 

 miersi, 31. princeps, Halisaurusfraternus, now Baptosaurus fraternus, 

 and H. platyspondylus, now B. platysioondylus. 



Prof. Leo Lesquereuxg described, from the Dakota Group, at Fort 

 Ellsworth, Nebraska, Pojnilites microphyllus, Phyllites betuloifolius, 

 Persea oiebrascetisis, now Laurus nebrascensis, and Sassafras leconte- 

 anum, now Persea leconteana. 



The Cretaceous is the lowest formation exposed in Louisiana,! 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, Woodbur}-, 

 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 unconformably upon the coal measures beneath, 

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

 westerly. 



* Proc. Amer. Phil. Soc. 

 t Proe. Bost. Soc Nat. Hist. 



I Am. Jour. Sci. aud Arts, 2d ser., vol. 48. 

 § Trans. Am. Phil. Soc, vol. 13. 



II Geo. of Lou., 1870. 



IT Geo. Sur. Iowa. 1870. 



