122 PROGRESS OF SCIENCE. 



America, but especially from the rich sepulchre of Colorado, 

 hundreds and hundreds of extinct animals, so that where, in 

 some instances, only one bone, one tooth, one vertebra of a 

 skeleton was known, we now have entire specimens, and speci- 

 mens not of one species, but of twenty, fifty, eighty species. 

 Just as Lamarck investigated and explained fossil shells, or 

 Cuvier the fossils of quadrupeds, so Prof. Marsh has laid 

 bare before us the Dinosaurian world of the Secondary Period 

 the world, that is, of the huge monsters which were then 

 the lords of creation. The specimens he discovered are so 

 very numerous that he has divided the Dinosaurs (four- 

 footed reptiles or lizards some herbivorous, some carni- 

 vorous) into five sub-orders, and these into genera, the 

 animals ranging in size from 2 feet in length to 60. Of the 

 nine great orders of Reptilia which existed then, the snakes, 

 tortoises, crocodiles, and lizards alone survive. The Cera- 

 tosaur was 17 feet, the Megalosaur and the Apatosaur 40, 

 the Diphodocus and the Cetiosaur 50, the Brontosaur 60. 

 The Atlantosaur was 30 feet high and 80 feet long; his 

 thigh-bone was over 6 feet ! The Triceratops had a skull 

 6 feet long. The Scelidosaur was covered with spines all 

 over his back. The Stegosaur was armed from his head 

 to his tail with a ridge of erect plates on his back, almost 

 triangular in form and some 2 or 3 feet in diameter, and 

 the end of his tail was bristling with four pairs of powerful 

 spines from I to 2 feet long. He had two brains a small 

 one in the skull, and another, ten times as large, in the 

 sacrum close to the haunches. When we bear in mind 

 that some of these monsters, as large as or larger than ele- 

 phants, could walk on their hind legs and could have 

 looked in our houses through a window on the second 

 storey, we can imagine what a stupendous spectacle they 

 presented. Prof. Marsh, likewise, found as many as 60 

 species of Mosasaurs sea-serpents ranging from 10 to 80 

 feet in length. He made out four species of Pterosaurs or 

 Pterodactyls flying reptiles the largest of these measuring 

 25 feet across the wings. The Dinocerata huge mammals 

 not unlike the rhinoceros were found to have formed no 

 less than thirty species. Marsh discovered, in the Eocene 



