KEPORT OP NATIONAL MUSEUM, 1913. 55 



The exhibition iii invertebrate paleontology begins with a large 

 mount showing a Cambrian sea beach, with numerous ripple marks 

 and animal tracks crossing the sandstone. Large slabs illustrating 

 the various types of near-shore sedimentation with their contained 

 fossil remains, and colonies of Cretaceous, Devonian, and Mississippian 

 crinoids, further represent the occurrence of ancient hfe; while the 

 superposition of various rock formations is shown by means of a 

 geological column of the strata found in New Hampshire. A case of 

 specimens from the Middle Cambrian deposits near Field, British 

 Columbia, serves to demonstrate both the significance of a fossil 

 fauna and the perfection of preservation sometimes obtaining 

 among fossil forms. Next are illustrated the general methods of 

 fossilization and the usual conditions of preservation of fossils, 

 followed by a number of cases devoted to the evolution of all the 

 important groups of fossil invertebrates. The very rare medusae, 

 the crinoids and the insects are especially well represented in this 

 series, though in no group is the material scanty. For the student 

 of geology a stratigraphic series of the common and characteristic 

 fossils of the various geological horizons of North America, accom- 

 panied by hand specimens of the characteristic rocks of each forma- 

 tion, occupies an adapted form of American case which extends 

 uninterruptedly along the north wall. Mounted directly above 

 this exhibit is a continuous geological section across the American 

 continent on a scale of 2 miles to the inch, and measuring 90 feet 

 long. Lack of space has prevented the introduction of collections 

 illustrating geographical distribution in any detail, the only exception 

 in this regard being the I. H. Harris collection from the widely-known 

 Cincinnati region, which is displayed in 2 cases. 



On account of their great variation in size, it has not been feasible 

 to arrange the exhibits in vertebrate paleontology as systematically 

 as in the two other sections of the division. In a general way, 

 however, the western half of the large hall has been mainly allotted 

 to the larger mammals, and the eastern part to the reptiles and birds. 

 Occupying the center of the floor, immediately after entering from 

 the rotunda, is the restored skeleton of an immense whale-like 

 creature, popularly known as the zeuglodon (Basilosaurus) , which 

 inhabited the seas of the southern coastal plain of the United States 

 in early Tertiary times. While numerous fragments of the bones 

 of this animal have been found, the specimen on exhibition is the 

 most perfect one known. To the right and left, respectively, of the 

 zeuglodon, are quite complete skeletons of the American mastodon 

 {Mammut americanum) from the peat bogs of Michigan, and the 

 giant deer (Alee gigantea), commonly termed the Irish elk, from 

 the Pleistocene clays of Ireland. Series of smaller specimens are 

 arranged in cases and framed mountings along the walls, among them 



