51 



ERA OF THE NEW RED SANDSTONE 



TERRESTRIAL, ZOOLOGY COMMENCft WITH REPTILES. 

 FlRST TRACES OF BIRDS. 



The next volume of the rock series refers to an era dis- 

 tinguished by an event of no less importance than the 

 commencement of land animals. The New Red Sand- 

 stone System is subdivided into groups, some of which 

 are wanting in some places ; they are pretty fully deve- 

 loped in the north of England, in the following ascending 

 order : 1. Lower red sandstone ; 2. Magnesian limestone; 

 3. Red and white sandstones and conglomerate ; 4. Varie- 

 gated marls. Between the third and fourth there is, in 

 Germany, another group, called the Muschelkalk, a word 

 expressing a limestone full of shells. 



The first group, containing the conglomerates already 

 adverted to, seems to have been produced during the time 

 of disturbance which occurred so generally after the car- 

 bonigenous era. This new era is distinguised by a pau- 

 city of organic remains, as might partly be expected from 

 the appearances of disturbance, and the red tint of the 

 rocks, the latter being communicated by a solution of oxide 

 of iron, a substance unfavorable to animal life. 



The second group is a limestone with an infusion of 

 magnesia. It is developed less generally than some others, 

 but occurs conspicuously in England and Germany. Its 

 place, above the red sandstone, shows the recurrence of 

 circumstances favorable to animal life, and we accordingly 

 find in it not only zoophytes, conchifera, and a few tribes 

 of fish, but some faint traces of land plants, and a new and 

 startling appearance — a reptile of saurian (lizard) charac- 

 ter, analogous to the now existing family called monitors. 

 Remains of this creature are found in cupriferous (copper- 

 bearing) slate connected with the mountain limestone, at 

 Mansfield and Glucksbrun, in Germany, which may be 

 taken as evidence that dry land existed in that age near 

 those places. The magnesia limestone is also remarka- 

 ble as the last rock in which appears the leptaena, or 

 producta. a conchifer of numerous species which makes a 

 conspicuous appearance in all previous seas. It is like- 

 wise to be observed, that the fishes of this age, to the 

 genera of which the names palaaoniscus, catopterus, pla- 



