VERTEBRATE LIFE IN AMERICA. 523 



the Glyptosauridce, were protected by a highly-ornamented bony coat- 

 of-mail, and others were covered with scales, like recent lizards. A 

 few resembled, in their more important characters, the modern igua- 

 na. The genera best represented in the Eocene are Glyptosaurus, 

 Iguanavus, Oreosaurus, T/iinosaurus, Tinosaurus, and Saniva. Some 

 of these genera appear to have continued into the Miocene, but here, 

 as well as in the Pliocene, few remains of this group have been found. 

 It is not improbable that some of our extinct Reptiles may prove to 

 belong to Pi/nchocephala, but at present this is uncertain. The genus 

 JVbtosaurus, from Brazil, has biconcave vertebrse, and some other 

 characters which point to that group. No Dicynodonts ' or Therio- 

 donts 2 have as yet been found in this country. 



The first American serpents, so far as now known, appear in the 

 Eocene, which contains also the oldest European species. On the At- 

 lantic border, the genus Titanophis (Dinophis) is represented by 

 several species of large size, one at least thirty feet in length, and all 

 doubtless inhabitants of the sea. In the fresh-water "Western Eocene, 

 remains of snakes are abundant, but all are of moderate size. The 

 largest of these were related to the modern boa-constrictors. The 

 genera described are JBoavus, Ziithophis, and Limnophis. The Mio- 

 cene and Pliocene snakes from the same region are known only from 

 a few fragmentary remains. 



The Pterosauria, or flying-lizards, are among the most interesting 

 reptiles of Mesozoic time, and many of them left their remains in the 

 soft sediments of our inland Cretaceous sea. These were veritable 

 dragons, having a spread of wings of from ten to twenty-five feet. 

 They differed essentially from the smaller Pterodactyls found in the 

 Old World, in the entire absence of teeth, showing in this respect a re- 

 semblance to modern birds; and they possess other distinctive charac- 

 ters. They have therefore been placed in a new order, Pteranodontia, 

 from the typical genus Pteranodon, of which five species are known. 

 The only other genus is JSTyctosaurus, represented by a single species. 

 All the specimens yet found are from essentially the same horizon, in 

 the chalk of Kansas. The reported discovery of remains of this order 

 from older formations in this country is without foundation. 



The strange reptiles known as X>inosauria, which, as we have 

 seen, were numerous during the deposition of our Triassic shales and 

 sandstones, have not yet been found in American Jurassic, 3 but were 

 well represented here throughout the Cretaceous, and at its close be- 

 came extinct. These animals possess a peculiar interest to the anato- 



1 Dicynodonts (two canine teeth), a singular group of extinct reptiles from South 

 Africa, India, and the Ural Mountains. The family name alludes to the two enormous 

 canine teeth which grow from the upper jaw. 



2 Theriodonts (beast-tooth), a group of extinct reptiles, having, according to Owen, 

 some characters which point toward the Mammalia. 



3 See note on page 520. 



