1917] Fossil Bisects 5 



vania and West Virginia have lately been found by Mr. H. 

 Bassler to contain numerous faunulae, mostly cockroaches, 

 which I have been permitted to study. Scudder and Hand- 

 lirsch had already observed that practically every Paleozoic 

 locality yielded different species, and I have also found this to 

 be the case. Considering the number of species and localities 

 discovered by Mr. Bassler in a couple of years or so, we may 

 reasonably expect eventually to have a very good detailed 

 knowledge of the insects of the Pennsylvanian, and thereby 

 have the means of elaborating a very accurate stratigraphy of 

 the anthracite coal region. The tendency of all these studies is 

 to enlarge our conception of the duration of the Pennsylvanian, 

 which must represent an enormous amount of time. The main 

 outstanding question now is, can we not only distinguish all 

 these cockroach faunulae — as we certainly can — but also place 

 them, from the evidence afforded by the insects alone, in the 

 right order? In other words, can we recognize a direct forward 

 evolution, or are we again confronted by a shuffling process? 

 Before attempting to answer this, we must get rid of the idea 

 that regular progressive development necessarily occurred, and 

 only waits to be detected. In the Tertiary, were it possible to 

 restore the faunas of a million years ago to life, and place them 

 beside those existing now, there are certainly several groups, at 

 least, in which no entomologist could distinctly affirm which 

 was the more primitive. The best he could do would be to 

 point out that whereas both lots contained archaic genera, 

 there were rather more of these in the older series; and to do 

 this he would need very complete materials. 



Returning now to the Palaeozoic fauna we find, as Handlirsch 

 has pointed out in several papers, that insect life begins, so far 

 as we know it, with that remarkable group called Palaeo- 

 dictyoptera. The so-called Silurian insects are clearly value- 

 less, and the exact age of the oldest Palaeodictyoptera is still a 

 matter of dispute; Mr. G. F. Matthew still adheres to the opin- 

 ion that the remains from St. John, New Brunswick, are of 

 Devonian age. He points out that cockroaches are entirely 

 absent, that Devonian genera exist among the accompanying 

 plants, and that a later (Mississippian) facies is due to the fact 

 that the deposits represent an old delta plain, whereas other 

 known Devonian plants are from what was hilly country or 

 sea-coast. On the other hand Kidston and David White, 



