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SAMUEL H. SCUDDER OX THE 



and five of Blattinarise having been added, the base of separation may still be maintained. 

 It has been stated by Brongniart that Mylaci-idœ occur at Commcntry in France, the richest 

 deposit of Carboniferous insects yet discovered, and that other distinctions, drawn from the 

 form of the prothorax exist between the two groups ; but the distinctions he makes cannot 

 be maintained for the American forms, and until the publication of specific descriptions or 

 figures we cannot consider the presence of Mylacridœ in European rocks as proven. I ought, 

 however, to add that Mr. Brongniart has recently shown me specimens which, on cursory 

 examination, looked like Mylacridse of the type of Necymylacris, i.e., approximating the 

 Blattinarise. 



"With these preliminary statements let me direct attention to the following tables of 

 geological and geographical distribution of the genera of fossil cockroaches in America, and 

 particularly of the older forms. The first table presents in a summary form the number of 

 species of each of the different genera found in the American Palaeozoic rocks in the several 

 coal basins and in two special localities in Ohio and West Virginia, where the greatest 

 number of species have been found. 



TABLE SHOWING THE GEOGRAPHICAL DISTRIBUTION OF AMERICAN PALEOZOIC COCKROACHES. 



This table shows at a glance how largely the two genera, Etoblattina and Gerablattina 

 and especially the former, predominate, and that their predominance is due principally to 

 their a1)undance at the two localities in Ohio and West Virginia, which have furnished moi-e 

 than one-half the American cockroaches. These two localities are of recent discovery and 

 belong the one to the Barren Coal-measures, or the uppermost Carboniferous, the other, in 

 West Virginia, to the lowest Permian, in what has been called the Dunkard Creek series. 

 They include among them, in both these genera, cockroaches of a peculiar appearance. 



