AGE OF COAL. 



231 



als, crinoids, etc., brought out in relief by the long-con- 

 tinued action of the weather upon the stone. 



332. Articulates. Of the Crustaceans, but few of those 

 singular animals, the Trilobites, which numbered about 

 six hundred species in the Silurian, were present in the 

 Carboniferous age, and these were the last of that tribe. 

 Xew tribes appeared, of which one Avas very much like 

 the horse-shoe of the present day. Minute Crustaceans 

 swarmed in myriads in stagnant waters, as their remains 

 in the rocks now show. Of insects there have been 

 found some wing-cases of beetles. Insects of the cock- 

 roach tribe nourished then, and there were also some 

 scorpions. 



333. Reptiles and Fishes. Some reptiles appeared in 

 this age, foreshadowing the succeeding one, in which 

 they were to be so abundant and large as to give the 

 name of Reptilian to it. The remains of some have been 

 found, and tracks have been discovered which evidently 

 belonged to reptiles, no remains of which have as yet 

 appeared in the rocks. Fig. 134 represents two oAhe 



tracks of such a reptile, which 

 were found near Pottsville, in 

 Pennsylvania, by Dr. Isaac Lea, 

 of Philadelphia. In one part of 

 the slab there is the impression 

 of a tail. These marks, mingled 

 with ripple-marks and impres- 

 sions of rain-drops, making out 

 a most interesting record of that 

 age so far distant in the past 

 eternity, have been before no- 

 ticed in 210. Some of the 

 fishes of this age foreshadow 

 the succeeding Reptilian age, 

 by combining some of the reptilian characteristics with 

 those of fishes. Of such reptile fishes there is at the pres- 

 ent time but one known genus, the Lepidosteus, or gar- 



Fig. 134. 



