CLASSIFICATION. 15 



in sect- horizons have been found, and many new types recorded. Some of these 

 linking forms already known, and others indicate relationships not fully under- 

 stood. The retention of the Order Palaeodictyoptera has therefore resulted in the 

 formation of a somewhat heterogeneous assemblage, all members of which have 

 one point of agreement. They are primitive co-types, more nearly related to each 

 other in various ways than they are -to recent insects, although that relationship is 

 not always as demonstrable as one could wish. 



The most ambitious classification yet attempted is that of Prof. Lameere 

 (1917, 'Bull. Mus. Hist. Nat., Paris,' no. 1), who has published only a summary of 

 his conclusions. We are not able to determine how valid are his arguments, or 

 if he is justified by evidence in setting forth his new scheme. He sweeps the 

 Order Pala3odictyoptera wholly away, pointing out that it consists of a hetero- 

 geneous assemblage, and substitutes a more detailed classification as follows : 



SUBULICORNIA. 



EPHEMEROPTERA. 



Family. Spilapteridae. 



Genera. Lamproptilia, Brong. ; Epitethe, Handl. ; Becquerelia, Brong. ; 

 Palteoptihis, Brong. ; Compsoneura, Brong. ; Spiloptilus, Handl. ; 

 Homaloneura, Brong. ; Graphiptih(s,~Brong.; Spilaptera,~Brong. 

 Family. Megasecopteridse. 



Genera. Aspidothorax, Brong. ; Corydaloides, Brong. ; Diaphanoptera, Brong. ; 

 Cycloscelis, Broiig. ; Sphecoptera, Brong. ; Psilothorax, Brong. ; Mis- 

 choptera, Brong. ; Ischnoptilus, Brong. 

 Family. Protephemeridse. 



Genera. Apopappns, Handl. ; Triplosoba, Handl. 

 ODONATOPTERA. 



Family. Fouqueidae. 



Genei-a. Fouquea, Brong. ; Rhabdoptilus, Brong. 

 Family. Dictyoneuridae. 



Genera. Microdict ya, Brong.; Stenodidya, Brong. 

 Family. Dictyoptilidae (Protodouata). 



Genera. Arcli&megapiilus, Brong. ; Dictyoptilus, Brong. ; Poromaptera, Brong. ; 



Protayrion, Broug. ; Gilsonia, Brong. ; Meganeura, Brong. 

 EHYNCHOTA. 

 PROTOHEMIPTERA. 



Family. Homoiopteridse. 



Genera. Lycocercus, Handl. ; Homoioptera, Brong. ; Lithoptilus, Brong. 

 Family. Megaptilidse. 



Genus. Megapttius, Brong. 

 Family. Breyeridse. 



Genus. Megaptiloides, Handl. ; Borrea, Brong. 

 Family. Mecynostomidoa. 



Genus. Mecynostoma, Brong. 

 HEMIPTERA. 



Family. Dictyocicadidae. 



Genus. Dictyocicada, Brong. 



