Homoptera. 73 



eyes absent; pronotum, and usually abdomen with comb-like arrangements 

 of spines; species occurring on bats (Ceratopsyllus.) CERATOPSYLLID^ 



3. Spines of hind tibia? in a single row, or in pairs (PI. 13, figs. 306, 308) 4 



Spines of hind tibiae numerous, in close-set, short transverse rows on the hind 



border, about four spines in each row. (Hystrichopsylla.) 



HYSTRICHOPSYLim& 



4, Spines of hind tibiae in pairs and few in number, not in a very close-set row. 



(Pfflex [P. irritans, Human flea], Ctenocephalus [C. canis, Dog flea; C. felis, 

 Cat flea], XenopsyUa (= Laemopsylla) [X. cheopis, Tropical rat flea, Plague 

 flea], Ceratophyilus [C. fasciatus, Rat and plague flea of temperate regions]) 



(PI. 13, figs. 306, 307, 308, 309, 311, 312) PULICIIX& 



Spines of hind tibiae numerous, mostly single and in a close-set row. -(Ctenop- 

 syllus.) CTENOPSYLLIIXE 



ORDER HOMOPTERA. 



(RHYNCHOTA, part.) 



An assemblage of very diverse insects, difficult to define in a 

 general way; usually of moderate or small size, rarely large; in 

 the active forms four wings are present in both sexes; in the scale 

 insects only the males are winged, and they have the hind wings 

 absent; wings usually sloping over the sides of the body; fore 

 wings never modified into a heavy basal and thinner apical por- 

 tion; beak jointed, inserted at the hind edge of the head and ex- 

 tending between the front coxse, the basal joints very short, rarely 

 the beak is absent in the males; cerci wanting. Metamorphoses 

 usually incomplete, sometimes complete in the male, rarely so 

 in the female; all the species plant-feeders. 



1. Tarsi three-jointed; antennae very short, with a small terminal bristle; beak 



plainly arising from the head; active free-living species. (AUCHENOR- 



RHYNCHA.) 2 



Tarsi two- or one-jointed; antennae usually well developed, sometimes absent, 

 without conspicuous terminal bristle; beak appearing to arise between the 

 front legs, rarely absent in the male; species often incapable of moving, or 

 inactive in the female sex 14 



2. Three ocelli, placed on the disk of the vertex (PI. 16, fig. 376) ; antennae with short 



basal joint, terminated by a hair-like process which is divided into about 

 five joints; front femora thickened and generally spined beneath; male with 

 a sound-producing organ on each side at the base of the abdomen; com- 

 paratively large species. (Cicada [C. septendecim, Periodical Cicada], 



Tibicen, Platypedia) (PI. 15, figs. 348, 349) CICADDXE 



Two ocelli, rarely three or more 3- 



