SUBPHYLUM III 



INSECTA 



809 



Scudder suggested, the lingering fragments of an expiring groiip. The genera 

 Cronicus Eaton (Fig. 1566) ; Palingenia Burm. ; Baetis Leach ; and Ephemer a Linn. 

 occur in Baltic aniber, and the last-nained is found also in the Miocene lake beds of 

 Florissant, Colorado. 



t Order 26. PROTODONATA Brongniart. 



Mostly very large Insects ivith large eyes and heavy jaws ; segments of the thorax 

 unequal ; legs stout, homonomous. Wings suhequal, horizontally expanded and with a 



Meganeura monyi Brongn. 



Fig. 1567. 



Stephanian (Upper Productive Goal Measures) ; Commentry (Allier), France. 

 i/g (after Brongniart). 



finely reticulated venation ; the hinder pair somewhat dilated towards the hase, without 

 folds. Nodus, pterostigma, wing triangle, quadrangle, reduction of the anal vein, and 

 other characteristic wing structures of the true Odonata are not developed in this order. 

 Sector radii and media prohahly not crossed. Abdomen slender. 



This group is of traiisitional character between the Palaeodictyoptera and the true 

 Odonata or diagon-flies. Its geological ränge is from the Goal Measures to the Trias, 

 and the several genera belonging to it are grouped under the families Protagrionidae, 

 Meganeuridae and Paralogidae. In all, less than a dozen species are known, only 

 three of which are North American. These last are referred to the genera Paralogus 

 Scudder, typified by F. aeschnoides from the Goal Measures of Ehode Island ; Palaeo- 

 therates Handlirsch, from the corresponding horizon in Pennsylvania ; and Tupus 

 Sellards, from the Permian of Kansas. The gigantic Meganeura Brongn. (Fig. 1567), 

 from the Upper Goal Measures (Stephanian) of Gommentry, France, measured over 

 75 cm. across the extended wings. 



