212 DOUGLASS — CRETACEOUS AND LOWER TERTIARY. [Aprils, 



Some hard limestone concretions are crowded with these small 

 molluscs. 



What distinguishes the Pierre here from that in other places is 

 the presence of many vertebrate fossils. Several Mosasaurs have 

 been found. In the summer of 1900, Mr. Albert Silberling and I 

 found portions of two individuals, including a skull. In the sum- 

 mer of 1901, the Princeton Expedition in charge of Dr. M. S. Farr 

 procured a nearly complete skeleton except the skull. 



But the most interesting fossil remains are those of the Dinosaiws. 

 They have been found to be more numerous here than the Mosa- 

 saurs. The greater number of them belong to the genus Claosaurus 

 and apparently to described species. Two portions of skeletons 

 belong to quadrupedal type, probably to the Cerafopstd(3. A C/ao- 

 saurtis skull and the greater part of the skeleton was obtained for 

 the Princeton Museum last summer (190 1). The digging was easy, 

 but the removal of the bones was slow and tedious, as they had to 

 be hardened. Nodules had formed around some of them, but 

 many were in clear shale. The skeleton was just above a layer of 

 yellowish, partly consolidated sandstone two or three inches in 

 thickness. There were some thin layers or lenses in the shale, in 

 which the remains were imbedded. There was also a minute seam 

 of coal not thicker than cardboard. Cones or ends of twigs of 

 what appeared to be Sequoia, Ammonites, Scaphites, Baculites and 

 other molluscs, and shark's teeth were found in the matrix while 

 removing the skeleton. Only the teeth and a few of the shells 

 could be preserved, as the fossils in the shale disintegrated on 

 exposure to the sun and rain. The deeper into the shale excavation 

 was made, the larger the flakes into which it would break. Quite a 

 number of other portions of skeletons were found during this and 

 the previous year. Often the bones are solid, though lying among 

 the grass roots, where the soil is composed of the disintegrated 

 shales. Sometimes the nodules surrounding the bones are very hard 

 and flinty. 



The finding of Dinosaur remains in these marine beds was un- 

 expected, but the sea was evidently shallow. In some places there is 

 much gypsum in good-sized crystals, or in minute ones scattered 

 through the shales. 



The Pierre beds being soft, have weathered into depressions. 

 They are usually covered, except in restricted portions, with a good 

 growth of grass, but are treeless except for a few small willoAvs or 



