630 THE INSECTS OF ANCIENT AMERICA. 
While no definite conclusion can be drawn concerning 
the age of the rocks in which these remains occur, there 
can be little doubt that they belong to the Tertiary epoch. 
Professor Denton believes them to be at least as old as 
the Miocene. 
The species of fossil insects now known from North 
America, number eighty-one: six of these belong to the 
Devonian, nine to the Carboniferous, one to the Triassic, 
and sixty-five to the Tertiary epochs. The Hymenoptera, 
Homoptera, and Diptera occur only in the Tertiaries ; the 
same is true of the Lepidoptera, if we exclude the Mor- 
ris specimen, and of the Coleoptera, with one Triassic 
exception. The Orthoptera and Myriapods are restricted 
to the Carboniferous, while the Neuroptera occur both in 
the Devonian and Carboniferous formations. No fossil 
spiders have yet been found in America. 
EXPLANATION OF PLATE 16 
Fig. 1. Miamia Bronsoni. A neuropterous insect found in iron- 
Fig. 2. Archimulacris Acadica. Wing of a PERS observed by 
Mr. Barnes in the coal-formation of Nova Scoti 
Fig. 3. Platephemera antiqua. A gigantic Mirer obtained by Mr. 
Hartt in the Devonian rocks of New Brunswick. 
Fig. 4. Xylobius sigillariæ. The Myriapod (or Gally-worm) found 
in the coal-formation of Nova Scotia, by Dr. J. W. Dawson. Copied 
‘from a figure in Dr. Dawson’s Air-breathers of the Coal-period. Mag- 
ified. 
Fig. 5. Tietoni Hartii. A neuroptero sect, the specimen 
first discovered by Mr. Hartt in the pevedlank ener of New Bruns- 
wick. This fossil, and those accompanying it, are the oldest insect- 
remains in the world. 
_ Fig. 6. Three facets from the eye of an insect, considered by Dr. 
ae Dawson a Dragon-fy. It was found in coprolites of reptiles in the 
