344 NEUROPTERA chap. 



fragile forms have not been preserved in the rocks, or have not 

 attracted the attention of collectors ; but as some of the palaeozoic 

 Insects were absolutely the largest known surpassing consider- 

 ably in size any Insects at present existing it is probable that, 

 even if small forms existed at the remote epoch we are alluding 

 to, the average size of the individual was greater than it is at 

 present. The Megasecopterides of the carboniferous epoch were 

 Insects of large size, with long, narrow wings, a small prothorax, 

 and large meso- and meta-thorax, these two segments being equal 

 in size ; the abdomen was elongate and moderately voluminous, 

 and was terminated by a pair of very elongate, slender filaments 

 like those of the may-flies. The family includes several genera 

 and species found at Commentry. One of these forms, Cory- 

 daloides scudderi, is of great interest, as it is believed by Brong- 

 niart that the imago possessed tracheal gills situated on the 

 sides of the abdomen, analogous with those that exist at present 

 in the immature condition of certain Ephemeridae. They are of 

 interest in connexion with the gills found at the present time in 

 the imagos oi Pteronarcys (seep. 401). Although these fossils 

 are of such enormous antiquity, the tracheae can, M. Brongniart 

 says, be still perceived in these processes. 



The Platypterides include also a considerable number of 

 Insects of large size, with four large equal wings, frequently 



spotted or variegate. Some of 

 these Insects were provided 

 with expansions or lobes on 

 the sides of the prothorax 

 (Fig. 213); these are looked 

 on as analogous to the ex- 

 pansions of meso- and meta- 

 thorax, which are supposed by 

 some writers to have been 



FIG. nZ.-LUhornantis carhonaria. Car- ^^^ rudiments from which 

 boniferous strata of Commentry, France. wingS Were developed. These 



(After Brongniart.) prothoracic wing -rudiments, if 



such they be, are said to have a system of nervures similar to 

 what we find in true wings. The genus LitJiomantis includes a 

 Scotch fossil, and has already been mentioned by us on p. 259. 



The third family of extinct carboniferous Neuroptera is the 

 Stenodictyopterides, in which Brongniart places the Dictyoneura of 



