ARTHROPOD A— INSECT A. 



427 



in a vertical direction. Head rounded, of moderate size, eyes dis- 

 tinct ; antennae not very long, and simple ; mouth parts fitted for 

 chewing; thorax of three similar segments, the first mostly with 



Fig. 1726. Haplophlebium barnesii, wing embedded in rock, with frond of fern ; 

 a, profile of base of wing. (After Dawson.) 



small wing-like appendages. Wing-veins almost exactly corre- 

 sponding to the hypothetic type (Fig. 1724). C marginal not 

 branched ; Sc independent, not far removed from C, not furcate ; 

 R simple, preserved 'to the tip; Rs separating from R near the 

 base of the wing, its branches mainly oblique to the apical border ; 

 M and Cu each generally with a simple or slightly dichotomous 

 anterior branch, and a more strongly branching inferior one, their 

 branchlets always more or less arcuate, and directed backward; 

 anal veins always well developed, more or less branched and 

 curved back to inner margin; cross-veins generally abundant and 

 irregularly distributed ; no anal fold or fan-hke plaitings. Legs 



Fig. 1727. J/omolhetus fossilis, X !• (After Scudder. ) 



similar, moderately long and strong, fitted for running; tarsus of 

 several joints. Abdomen moderately slender, never very thin or 

 very broad, uniformly segmented; eleventh segment with several 

 jointed, and often long, cerci. Larva similar to imago. 



