THE JURASSIC PERIOD. 



105 



latter by cockroaches, crickets, etc. To these were added many 

 beetles of several different families, some Hemiptera, the earliest known 



Fig. 378. — Lower jaws of American non-placental (polyprotodont) mammals of the 

 Upper Jurassic, a, Priacodon ferox; b, Drydestes vorax. One and one-half times 

 natural size. (After Marsh.) 



Diptera, represented by flies, and the earliest known Hymenoptera, 

 represented by ants; but the Lepidoptera (butterflies and moths) were 

 yet awaiting the appearance of the flowering plants. 



Little that is new relative to the life of the fresh waters is revealed 

 by the Jurassic strata. 



