HI. Palaeozoic Cockroaches : A complete Revision of the Species of Both 

 Worlds, with an Essay toward their Classification. By Samuel H. Scudder. 



_L HE study of fossil insects has hitherto furnished very little material toward a knowledge 

 of the general laws which have governed the progress of animal life. The reason of this 

 is not far to seek. The delicate nature of their framework is such that they are never 

 found preserved in any abundance, and seldom in such condition as to preclude doubts as 

 to their affinities ; the number of extinct known forms bears, indeed, a very small propor- 

 tion to that of other fossils. Moreover, the most important period in the history of any 

 group of animals is its earliest; and while the later appearance of mammals, creatures 

 possessing a bulky framework less liable to destruction, enables the naturalist to recon- 

 struct wdiat must be a very significant part of the primitive mammalian faunas, the very 

 early appearance of insects, with their fragile framework, is a serious obstacle to obtaining 

 any light whatever concerning their origin. Fragment by fragment have the few facts 

 been patiently gleaned ; yet to-day we possess for the entire palaeozoic period not more 

 than one species of insect to every thousand existing forms. 1 A few scattered generaliza- 

 tions concerning these earlier insects have been attempted, and in the preceding paper I 

 endeavored to collect all that was known upon the subject, and to show that some general 

 statements might be made, not likely to be gainsaid by further facts. The present paper 

 discusses with greater fulness the cockroaches of the palaeozoic period, a group which 

 contains fully one half the species of insects known from the ancient rocks, and therefore 

 one most likely to be fruitful in results. 



Their remains were first made known by Germar 2 in 1842, in Count Minister's Beitrage 

 zur Petrafactenkunde, where four species from Wettin were described and figured. Soon 

 afterwards, in his general work on the fossils of Wettin and Lobejiin, Germar redescribed 

 these with as many more; and additional forms have been published from time to time by 

 Goldenberg, Heer, E. Geinitz and others, until the number of European species at present 

 recognized in the palaeozoic rocks is about forty. To find the original descriptions of these 

 forty species one must look for no less than sixteen different papers by seven different 

 writers; rarely, too, have any of them received any further study after their original 

 description; it necessarily follows that our knowledge of them is very fragmentary, and a 

 worse showing could be made were we to include the American species, of which descrip- 

 tions of seven have appeared on six separate occasions. 



1 Compare this with the ratio of fossil to living mammals, 2 One species had been previously described, but as a lorn 



as seen in the list given in Murray's Geographical Distribu- leaf, 

 tion of Mammals, pp. 320-64. 4°. London, 1866. 



