Section IV., 1894. [ 147 ] Trans. Roy. Soc. Can. 



XII. — The Fossil Cockroaches of North America. 



By Samuel H. Scudder. 



(Presented by Mr. James Fletcher.) 



Although not in favour with the general public, the cockroach is to the palaeontologist 

 the most interesting of insects ; for it alone occurs at every horizon at which insects have 

 been found in abundance, and it is so dominant in the Carboniferous period, when insects first 

 existed in large numbers, as to have led me to call this period, so far as its insect fauna is 

 concerned, the " age of cockroaches." Its existence to-day is an example of the persistence 

 of an antique but now waning type. 



Fifteen years ago when I published a revision of the fossil cockroaches of the world - 

 only nineteen American specimens had been seen, representing seventeen si^ecies and seven 

 genera. To-day more than three hundred and fifty- American specimens have passed under 

 my eye, and from the Palseozoic series alone I have recognized among these no less than one 

 hundred and thirty-two species belonging to fourteen genera. A recent study of all these 

 forms, soon to be published by the U. S. Geological Survey', ofl'ers an occasion for some 

 general remarks upon them which have some interest. 



In 1879 1 claimed that Palaeozoic cockroaches, with which we are most concerned to-daj', 

 i.e., those known from Carboniferous and Permian rocks, differed from modern forms of 

 cockroaches to such au extent and by such characters as to warrant our separating them 

 bodily as a group under the name of Palseoblattarise. This view has been attacked, but 

 I think unsuccessfully, and every new discovery since then (the number of fossil species 

 having been multiplied many fold) has only strengthened my position : that Palaeozoic 

 cockroaches difl:er from modern forms in the far greater similarity of the fore and hind 

 wings in texture and venation ; by the presence in the fore wings of the full comi:)lement 

 of principal veins, some of which are completely or almost completely amalgamated in 

 modern forms ; and by the course of the anal veinlets, which as a rule ran in ancient times 

 to the hind margin of the wing parallel to each other, while now they strike the anal furrow 

 or collect apically in a bunch near its tip. This view has received no modification whatever 

 liy later discoveries, except that we find in certain Triassic rocks of Colorado an assemblage 

 of forms, partly Palseoblattarise, partly Xeol)lattariœ, in some of the latter of which the anal 

 veins preserve their ancient course. 



In further classification of these extinct cockroaches I then separated the American 

 forms into two groups, Mylacridse and Blattinariie, hy the structure of the mediastinal vein 

 of the fore wings. All the then known European forms were classed in the Blattinarise. 

 Now although the number of American Palaeozoic genera has doubled, two genera of Mylacridae 



' Published by permission of the Director of the U. S. Geological Survey. 

 2 Mem. Bost. Soc. Nat. Hist., vol. iii., pp. 23-134, pi. 2-6. 



