Vol. xxx 



!: N TOM ( ILOG1 CAL NEWS. 



43 



ed, although not belonging to the' same order) are anatomically 

 intermediate between the other Apterygota and the Pterygota, 

 and are therefore placed at the base of the stem. The fossil 

 Palaeodictyoptera seem to be very near the first winged in- 

 sects to be evolved, and are therefore placed a little above the 

 Lepismoid forms in the diagram. The Ephemerida are very 

 closely connected with the Palaeodictyoptera, and also ex- 

 hibit undoubted affinities with the Plecoptera, so that it is 

 extremely difficult to determine whether to group them with 

 the Palaeodictyoptera, or with the Plecoptera or even in a 

 distinct group to which the strongly aberrant order Odonata 

 should be added. The Ephemerida are placed a little above 

 the Palaeodictyoptera, since they are among the most primi- 

 tive living winged insects known, (although in some features 



GRYLLIDAE 



"LOCUSTIDAE" 



PHASMODIDAE 



GRYLLOBLATTIDAE 



ISOPTERA 

 MANTIDAE 

 BLATTIDAE 



TRI DACTYL I DAE 

 ACRIDIDAE 



PHASMIDAE 



DERMAPTERA 



EMBIIDAE 

 PLECOPTERA 



EPHEMERIDA 



PALAEODICTYOPTERA 

 LEPISMOIDEA 



