488 MODERN CLASSIFICATION OF INSECTS. 
exhibit various remarkable modifications of structure of different or- 
gans to which I can but thus refer. In Edessa, Acanthosoma, &c. the 
sternum exhibits several forms, the prosternum and mesosternum in 
the last-named genus being considerably produced into a porrected 
horn (fig. 121.17.). 


Orver APHANIPTERA Kirby. 
(Suctorta De Geer; StpHonartTerRA Latreille; AprtERA Lamarck, 
MacLeay ; Ruyneora p. Fabricius.) 
Cuar. Wings four; minute scaly plates applied to the sides of the 
body, those of the metathorax being the largest. 
Body compressed ; tarsi 5-jointed; antennz minute. 
Mouth formed for suction; mandibles and lingua long and seti- 
form; maxillz small, triangular scales with 4-jointed palpi; labium 
minute, with 3-jointed palpi. 
Larvee vermiform ; pupa inactive, incomplete. 
This order is composed only of the different species of fleas, forming 
the family PuLicipm * (fig. 123.1. Pulex irritans @ magnified; 2. 

* Brieriocr. Rerer. To tHE Puricipa. 
Leuwenhoeck. Arcana Nature, tom.i. 
Paullini. De Pulicibus in Ovo, Mise. Acad. Natur.’Curios. Dee. 3. 1695-6. 
D. Jacinta Cestoni. A new Discovery of the Origin of Fleas, Phil. Trans. 1699. 
Latreille. Obs. sur Hist. Nat. de la Puce, in Rapport Gen. des Travaux de la 
Soe. Philomat. tom. ii., Paris 1798. 
Defrance. Notes sur la Puce irritante, in Ann. Sci. Nat, tom. i. 1824., and Zool. 
Journ. No. 2. 
Duges. Recherches sur 1. Caract. génér. du Pulex, in Ditto, tom. xxvii. 1832,— 
Ditto, on Pulex penetrans, in Ditto, September 1836. 
Bose. Descr. dune Esp. du Puce (P. fasciatus. ), in Bull. Soe. Philom. No. 44. 
Fabricius, in Dansk. Vidensk. Selsk. Skrivt., n. Saml. D. 2. (n. sp. Pulex). 
Weiss. Observ. de Pulice, in Acta Helvet. vol. v. 
Vollmar, in Gistl’s Faunus, 1837, No. 2. (Pulex penetrans), 
Schonherr, in Kong]. Vetensk. Acad. Handl. 1811. (Pulex segnis). 
Macquart, in Ann. Sci. Nat. April 1831. - 
Swartz, On Pulex penetrans, in Vetensk. Acad. Hand]. 1788. 
Bouché, in Nov. Act. Acad. Czs. Nat. Curios. vol. xvii. p. 1. (Monogr. Pulex),. 
Guerin. Tcon. R. An. Ins,, and description of ditto. 
