S. H. SCUDDER ON THE EARLY TYPES OF INSECTS. 21 



7. Nearly all the palaeozoic Orthoptera belong to the lower non-saltatorial families, 

 and are almost exclusively cockroaches. 



8. The Neuroptera proper were at that time much rarer than the lower Pseudoneur- 

 optera. 



9. All the earlier types were therefore of inferior organization. 



10. The general type of wing structure in insects has remained unaltered from the 

 earliest times. 



11. With the exception of two species of Coleoptera and one of Orthoptera, the front 

 and hind wings of palaeozoic insects were similar and membranous, heterogeneity making 

 its appearance in mesozoic times. At the same time, the neuration of the wings of palae- 

 ozoic insects in otherwise widely diverse types was much more similar than now. 



12. The series of facts presented to us by the progress of geological research leads to 

 the conviction of the probable existence and possible discovery, in the Devonian and even 

 in the Silurian formations, of winged insects, still more generalized in structure than any 

 yet detected in the palaeozoic rocks. 



It may also be added that nearly all the earlier insects were large, many of them 

 gigantic in size, and, further, that there is a striking similarity between the carboniferous 

 insect-fauna of Europe and North America. 



Note. The preceding pages were printed before I chanced upon the following passage from Lacordaire 

 (Introd. a l'entom. I, p. 326), which may be taken as a note to the last paragraph of third page of this paper: — 



" Toutes les differences que l'on observe dans le thorax des Insectes proviennent du plus ou nioins de devel- 

 oppement qu'a pris chaque anneau thoracique, du nombre de pieces que chacun d'eux presente, et de la 

 grandeur relative de chacune de ces pieces en particulier. Si le prothorax a acquis un developpement extra- 

 ordinaire, et s'est en quelque sorte separe du mesothorax et du metathorax, on aura le thorax d'un Coleoptere, 

 d'un Dermaptere, d'un Orthoptere et d'un Hemiptere. Si au contraire le prothorax est reduit a des dimensions 

 tres-exigues, et que le mesothorax intimement uni au metathorax ait pris un aecroissement enorrne, on aura 

 celui d'un Hymenoptere, d'un Lepidoptere et d'un Diptere." 



