286 THE OLDEST AIR-BREATHERS 



examination of this excrementitious matter. It contains much 

 carbonate of lime, indicating that snails or other mollusks 

 furnished a considerable part of the food of the smaller rep- 

 tiles. Some portions of it are filled with chitinous fragments, 

 parts of millipedes or insects, but usually so broken up as 

 scarcely to be distinguishable. One curious exception was a 

 part of the head of an insect containing a portion of one of its 

 eyes. The facets of this can be readily seen with the micro- 

 scope, and are similar to those of modern cockroaches. About 

 250 of these little eyes are discernible, and they must have 

 been much more numerous. Two points are of interest here : 

 First, the perfection of the compound eye for vision in air. 

 It had long before, in the case of the Trilobites, been used for 

 seeing under water. Secondly, the great age of the still ubi- 

 quitous and aggressive family of the cockroaches. In point of 

 fact the oldest known insect, the Protoblattina of the Silurian, 

 is one of these creatures, and they are the most abundant in- 

 sects in the Carboniferous, so that if they now dispute with us 

 the possession of our food, they may at least put in the claim 

 of prior occupancy of the world. In one mass a quantity of 

 thickish crust or shell appears, which under the microscope 

 presents a minutely tubular and laminated appearance. It may 

 have belonged to some small crustacean or large scorpion on 

 which a Dendrerpeton may have been feeding before it fell into 

 the pit in which it was entombed. 



In addition to the reptilian species above noticed, the erect 

 trees of Coal Mine Point have afforded several others. There 

 is a second and smaller species of Dendrerpeton (D. Owent) 

 and other forms belonging to the group of Microsauria of which 

 Hylonomus is the type. A second species of that genus (H. 

 Wymani) has already been mentioned. A similar creature, but 

 of larger size and with teeth of a wedge or chisel shape, has 

 been referred to a distinct genus, Smilerpeton, It seems to 

 have been rare, and the only skeleton found is very imperfect. 



