32 S. H. SCUDDER ON PALAEOZOIC COCKROACHES. 



and Progonoblattina near Oryctoblattina high in the series. Petrablattina has also been 

 placed very high, on account of the apparent amalgamation of all the principal veins next 

 the base, as they generally appear in modern types. 



On zoological grounds, then, Ave should look upon the Mylacridae as the older type, but 

 when we come to examine the geological record, we discover very little special corre- 

 spondence between these features of structure and the relative age of the insects in ques- 

 tion. Our oldest American species are Gerablattina fascigera and Petrablattina sepulta, 

 and probably Blattina venusta, all of which are Blattinariae, not Mylacridae ; the other 

 American members of the group of Blattinariae are found in all the rocks up to the permo- 

 carboniferous, while the Mylacridae are confined to the true coal-measures, unless Necym. 

 heros and Archiin. parallelwm fall below them. On the other hand, it is worthy of remark 

 that of the nine species placed highest in the entire series below, before their stratigraphi- 

 cal position was at all considered, and belonging to five distinct genera, Petrablattina 

 gracilis, Hermatoblattina lebachensis and perhaps Gerablattina balteala belong to the 

 permian or dyassic formation, and comprise nearly one half of the species certainly known 

 from that horizon. And it will be seen further on that much the largest percentage of the 

 European cockroaches (Blattinariae only) come from the upper carboniferous beds; of the 

 American (Mylacridae and Blattinariae) from below them. It must not be overlooked 

 however that the great mass of palaeozoic cockroaches as a whole come from the highest 

 carboniferous rocks, and that the stragglers that have been found below these uppermost 

 beds are far too few for us to base any safe generalizations upon them. 



As to the geological range of the species, it would appear as if it were always extremely 

 limited, did we not reflect that very few of the species are known by more than one 

 example. It has been claimed by Dr. E. Geinitz that five of the species first described 

 from the carboniferous series, viz. : Etobl. anthracophila, Etobl. carbonaria and Etobl. 

 didyma of Wettin, Anthracobl. spectabilis of Lobejiin, and Gerabl. Mahri of Manebach, all 

 from the uppermost carboniferous rocks, were also found in the lower dyas of Weissig. 

 He supports his statement by figures or descriptions in three instances, and in each of these 

 cases I shall show that the reference was incorrect: Etobl. didyma being referred below to 

 a distinct species, Anthracobl. sopita; Etobl. anthracophila to Etobl. flab ellata; and 

 Gerabl. Mahri to a second distinct species, Etobl. elongata. This result throws some 

 doubt upon the unsupported references in the two other cases, and while these remain in 

 doubt, 1 Etoblattina flabellata is the only species unquestionably found in both the carbon- 

 iferous and dyassic series of the old world. The only other European species said to have 

 been found at two distinct localities is Etobl. didyma, which Germar described from Wettin 

 and Mahr says has been repeatedly found at Umenau; but these places are at the same 

 horizon. 



In the new world the only instance of the discovery of a second specimen of any species 

 is in the presumed case of Gerablattina balteata, where one was found in what are termed 

 permo-carboniferous rocks, on account of some question as to their true horizon, and the 

 other in undoubted uppermost carboniferous rocks. The so-called permo-carboniferous 

 rocks, however, are deemed by some geologists as certainly upper carboniferous. 



3 Geinitz himself refers to Anthrac. speclabilin with a query. 



