LIBELLULID^. 



597 



much as in the Perlarice, and probably with the sides pro- 

 tected near the base by the deflected marginal and scapular 

 (subcostal) areas." Scudder shows that while the venation is 

 much the same as in Hemerobius, as stated by Professor Dana, 

 it also resembles that of the Sialidce and EphemeridcB and 

 Libellulidce. Gerstaecker thinks that Hemeristia "at least 

 stands nearer to the E'phemeridm than to any other famil3\" 

 (Bronn's Klasseu und Ordnungen des Thier-Reichs, vol. v.) 



LiBELLULiD.E Latreille. Dragon-flies, Devil's-darning-nee- 

 dles, or Mosquito Hawks, are readily known by the enormous 

 head and thorax, with the remarkably long, slender, cylindrical 

 abdomen. The head is large and globular, with immense eyes 

 often encircling the head. The large square thorax is remark- 



*Fis. 570. 



able for the small size of the tergal parts, while the pieces 

 composing the flanks are greatly enlarged, rising up especially 

 in front, taking the place of the prothorax, which is usually 

 very large in the Neuroptera generally, but is in this family 

 greatly aborted, as these insects scarcely ever walk. As in 

 the Ephemeridce the antennae are short and setiform, and 

 the mouth is not furnished with palpi. The wings* are large, 



* Fig. 579. Venation of a fore wing of Gomphus. Veins. — a, n, costal vein; b, 

 subcostal vein ; c, c, median vein ; d, submedian vein ; e, postcostal vein. Sectors — 

 (branches springing from areas, veins, cross-veins, or other sectors), fff, prlnci- 

 p;il sector; g, nodal sector; h, snbnodal sector; Ic, median sector; mm, short sec- 

 tor; n, upper sector of the triangle (normally a prolongation of rf); o, lovv^er 

 sector of the triangle (normally a prolongation of e); o', o", its brandies. (The 

 /igure gives an angle where o' bifurcates from o, which should have been a flow- 

 ing curve. Both n and o sliould have been engraved as springing fi-om the lower 

 angle of the triangle, /.) Cross-veins. — p, nodus; q, arc or arcnlus; n-r, - - - ante- 

 cubitals. (Tlie basal antccubital is wrongly engraved as dislocated with that of 



