24 S. II. SCUDDER ON PALAEOZOIC COCKROACHES. 



It is true that sonic slight suggestions have been made toward the classification of these 

 insects, but, as will be shown further on, without much success. With rare exceptions all 

 have been described under the generic term Blattina ; the species, however, have occasion- 

 ally been confounded, and their relationship to one another and to the cockroaches of later 

 times has never been seriously examined. This examination seems the more desirable for 

 two reasons. First; as a general rule, it is the upper wing of these creatures which has 

 been preserved, allowing the best comparison not only with their living representatives, but 

 with one another ; for, owing to the transparency of the front as well as hind wings of palae- 

 ozoic insects, the venation is remarkably distinct, and from the nature of the part preserved 

 is rarely displaced in fossilization. Second ; our opportunities for any generalizations con- 

 cerning palaeozoic insects are exceedingly limited ; and this group, as the most abundant 

 of all the ancient types, offers the most inviting field of research. It would appeal 1 , too, 

 that the known species are in reality only the fragment of a vast host which existed at 

 that time, but have left no further traces, a host so great as to render it suitable to charac- 

 terize the carboniferous epoch, so far as insects are concerned, as the age of cockroaches. 



This conclusion is drawn from two facts. Every new discovery of palaeozoic cockroaches, 

 with scarcely an exception, reveals new species, so that upwards of sixty different kinds are 

 enumerated in this paper, showing great diversity of structure, and seldom represented by 

 more than a single specimen ; this indicates that their petrifaction is a rare event, and that 

 the few relics we have really represent a vast horde. The second fact is the decreasing 

 representation of these insects in the rocks as we approach the present time, coupled with 

 a very generous allowance of cockroaches living at the present day. If we divide the time 

 which has elapsed since cockroaches appeared into three great divisions, corresponding to 

 the palaeozoic, mesozoic and caenozoic epochs, embracing the present period in the last- 

 named, we shall have, say, sixty species in the palaeozoic, thirty-five in the mesozoic and 

 only sixteen fossil species in the caenozoic (even including those occurring in that most 

 prolific insect-trap, the Prussian amber), with upwards of five hundred living species. 1 If 

 we then consider the present as a part of the pliocene, and take only five hundred species 

 as the number actually living in each of the three divisions of caenozoic time, making 

 fifteen hundred in all. and sixteen as the number now reported as existing in tertiary times ; 

 and, finally, assume the same ratio between the unknown and the known to have held in 

 the palaeozoic as in the caenozoic epoch, we shall have live thousand, six hundred and 

 twenty-five species as the number of palaeozoic cockroaches. Even if enormously exag- 

 gerated, this estimate will at least indicate the prodigious quantity of cockroaches which 

 then existed and give an additional reason for the present revision. 2 



Giebel, who published the first list of palaeozoic cockroaches, then supposed to lie only 

 eight in number/ brought them all under the generic term Blattina. and placed with them 

 also some of the mesozoic species. In a foot-note (p. 315) he promises to give a "careful 

 revision" of all the Wettin cockroaches, but this he has never done. 



Ileer, in his catalogue of fossil cockroaches, 1 was the first to attempt any division of the 

 palaeozoic forms; his classification was as follows: — 



1 This is certainly a low estimate of existing types. Brun- cosmopolitan distribution ami vexatious fecundity — the dom- 



ner in 1875 enumerated nearly four hundred species, and ination in short — of certain existing species of cockroach, 

 since that time enormous additions i'> lids family have been 'Giebel. 1 he Insecten und Spinnen der Vorwelt. 8°. 



made, particularly by de Saussure. Leipzig, 1856. pp. 318- l ii. 



- Perhaps we may fairlj add thai the caiK appearance and ' [leer. Vierteljahrschr. naturf. Gesellsch. Zurich. Jahrg. 



prevalence of cockroaches also explains in a measure the ix. pp. 287 el seq. (1864.) 



