312 Scientific Intelligence. 



acters, and poor material, which is nob to be despised but to be 

 used cautiously in determining the evolution of the Hexapoda. 

 He has taken as his motto : " Better a little certain than much 

 doubtful." 



The plan of the work is as follows : The introduction contains 

 an account of the more important morphologic characters and 

 their phylogenetic application. Main reliance is placed on the 

 morphology of the wing and on convergent evolution. The 

 introduction closes with a description of the hypothetic primor- 

 dial insect, the Protentomon. 



In Part I (pp. 13-51) are described the orders of recent insects 

 along with descriptions of the various terms used throughout 

 the work. Here are also given schematic figures to illustrate the 

 venation of the various types of wing. Part II (pp. 55-393) 

 treats of the Paleozoic forms, and throughout the work all the 

 species will be illustrated as far as possible. Part III (pp. 394— 

 640, as far as published) takes up the Mesozoic insects. Part IV 

 will treat of the Tertiary forms ; V, of the Quaternary ; VI will 

 give a summary of the paleontologic results attained ; VII will 

 present a short historical summary of the proposed system, and 

 the closing part, VIII, will include the new classification of the 

 Hexapoda and the author's conclusion on the phylogen of the 

 Arthropoda. 



The work teems with new names of all grades and .may cause 

 alarm to some ; yet when one considers for a moment the extraor- 

 dinary differentiation among living insects (there are about 

 360,000 described), it is seen that even with these hundreds 

 of new generic names a beginning only in paleo entomology 

 has been made. Fossil insects, as a rule, are but accidentally 

 entombed and the fact that nearly every wing reveals a new 

 species and often a new genus indicates how little of the myriads 

 of insects that lived at any given time is preserved ; the present 

 work treats of all extinct Hexapoda. 



Carboniferous. — There are no fossil insects known previous to 

 the Coal Measures or Pennsylvania^ the so-called insects of 

 the Silurian having proved to belong to a trilobite or are lusus 

 naturae. Those of the New Brunswick Little River group, sup- 

 posed to be of Devonian age, are here referred to the Upper 

 Pottsville (Pennsylvauian), a conclusion in harmony with the 

 paleobotanical results of Mr. David White. 



In the Upper Carboniferous the first undoubted insects appear 

 both in North America and western Europe. The climate is 

 assumed to have then been mild and damp, and free from frost 

 into the arctic regions. The insect-bearing beds were probably 

 the deposits of swamps and forest moors, and from them are here 

 recorded 546 good species and 267-poor ones. The former are 

 arranged in 252 genera, and while the greater number of these 

 have but from one to four species, yet there are a few having a 

 goodly number, as Phyloblatta with 89 ; Sysciophlebia, 45 ; 

 Orthomylacris, 11 ; Mylacridium, 16, and Poroblattina, 19. Of 



