On Synlhelic Types in Insects. 597 



mcnts, since the pro-thorax is large and broad. In the 

 meso-notum of Polystccchotes (Fig. 2,) we have the 

 praescutum forming a hirge portion of it, perhaps a little 

 larger even than the scutellum of the seg- ^'^^^- i- 2- 



ment. In the Lepidoj)tera this scutellum 

 is always large, while the pra)scutum is jY T p 



minute and concealed, since it is bent /'^^'S/ 



down in front of the ring, and is not seen [/\J 



from above ; therefore it is very anomal- 

 ous to find this piece in Gorgopis (Fig. 1,) ^J^^TXt^ 

 enlarged considerably and occupying a \J\y 



lozenge-shaped area, not hidden between C^^ 



the meso- and pro-thorax, but spread out 

 horizontally, and in the same plane with the large, broad 

 scutum. 



As will be seen in the figure the pro-thorax of the Neu- 

 ropter is broad and square, while that of the moth is as 

 usual very short and small. 



In Ilepialus the elongation of the middle region of the 

 body is effected by the unnatural length of the meta- 

 thorax, accompanying which is the enlarged pair of hind 

 wings, a character essentially neuropterous. The meta- 

 thorax in Gorgopis is nearly as long as broad, while in 

 other Lepidoptera it is but a third as long as broad ; the 

 scutum, which in the meso-thorax of Lepidoptera occupies 

 nearly the whole notal surface of that ring, is in the 

 succeeding ring divided into two halves, which are thrown 

 aside by the very large triangular scutellum, whose apex 

 joins the same part of a much smaller triangular piece in 

 front, the praescutum, which is always concealed in the Le- 

 pidoptera, but in Gorgopis (Fig. 1,) appears for the first 

 time upon the upper surface of the ring instead of be- 

 ing crowded down in between the two hinder segments 

 of the thorax. A figure of what I have just described 

 will iilutitrate well the same segment in Polystoe- 



