TRIASSIC INSECTS OF COLORADO. 459 



The few insects other than cockroaches emphasize the mesozoic aspect of the rest of 

 the fauna. 



"We have then at Fairphiy an assemblage of forms altogether different from anything 

 hitherto found in the paleozoic series on the one hand, or in the Jurassic beds on the other. 

 They show a commingling of strictly Jurassic forms with a larger proportion of types 

 which may be called upper carboniferous or licrmian with a distinct Jurassic leaning. 

 There is therefore a strong probability that the beds in which they occur belong to the 

 intermediate formation, the triassic. 



If this should be proved, Mr. Lake's discovery will have an added interest, from the 

 fact that almost nothing is known either of the plants or of the insects of this formation. 

 Of the plants, it is only necessary to point out that in the paucity of data, the upper pa- 

 leozoic aspect of the few vegetable remains from Fairplay can have but a negative value 

 beside the positive proof of the alliance of the insects to mesozoic forms. Of triassic in- 

 sects our Iniowledge is exceedingly meagre ; a single neuropterous larva from the Con- 

 necticut valley is all that the formation has hitherto yielded in this country. In Europe 

 we know of only four sjiecies, each, I believe, from a single specimen ; one of these is a 

 cockroach, but it is entirely different from any of the Fairplay species, and indeed from any 

 other known forms, so that we get no light from this quarter. 



So far as I know this is the first attempt to determine the age of a deposit from its in- 

 sect remains alone, and it is unfortunate for its acceptance by natvu-alists that the plants 

 give it, to say the least, no support, but rather are deemed by one competent to judge, to 

 be decidedly adverse to what is here claimed. 



The paleontological contradiction shown in the plants and animals of the Fairplay beds 

 is not unknown to American geology, as every one is aware, but I do not know that it 

 has been pointed out in this country at this horizon or in this direction, the discordance 

 appearing later in time, and the plants indicating a younger and not an earlier age than 

 the animals. An exactly pai-allel case appears to be shown in eastern Russia, for in dis- 

 cussing the poorer strata of Kargalinsk, which he refers to the permian, Twelvetrces 

 says, "as regards the flora [eleven species] the list has a paleozoic aspect, but a second- 

 ary one as respects the reptilians remains" [four species cited.] ^ 



All the specimens are in my own collection. 



PALAEOBLATTARIAE Scudder. 



Etoblattin-a Scudder. 



Etoblattina persistens sp. nov. 



PI. 41, fig. 7; pi. 42, figs. 10, 19. 



The fore wing is a little less than two and a half times as long as broad with a mod- 

 erately convex costal margin and apparently a full and well rounded apex. The medi- 

 astinal vein extends somewhat beyond the middle of the wing and is provided with 



'Quart. Jouru. Gcol. Soc. Loncl., xxx\in, 495. 



