89 



in its turn is divided into five joints and terminated uy tsvo strong 

 claws. The relative length of these tarsal joints is usually used as a 

 distinctive specific character. 



The ubdomen constitutes the largest part of the body, and is made 

 up of nine segments, the greater number of which are covered by 

 dorsal and ventral chitinous ]ilates, which overlap those of the segment 

 in front. The first segment, however, has a dorsal plate onlv ; the 

 second to the seventh are normally formed. The eighth segment has a 

 somewhat peculiar shape, and differs in the two sexes. In the female 

 the dorsal plate is largely developed at the expense of the ventral, the 

 latter being very much reduced ; while in tlie male the ventral plate is 

 about equal in size to the dorsal. The pygidium or ninth and last 

 segment, which _^i3 the smallest of all, is situated in a depression 

 in the eighth, and is comi>osed of three pieces, a dorsal and two 

 ventrals. The former is oval in shape and surrounded by a chitinous 

 ring which encloses 25-28 areoles, each of which bem-s in its centre a 

 small stiff bristle. In the male this segment is thrown vei'y much 

 farther up on the dors:,il surface than in the female. 



Respiration is can led on through a system of trachete, which, open 

 on the surface of the boily in ten j)airs of stigmata, two on each of the 

 thoracic rings and the seven anterior segments of the abdomen. 



The alimentary canal is composed of a sh-n-t straight oesophagus 

 opening into a cylindrical stomach, from which the food passes V)y a^ 

 short intestine to the anus, situate below the ninth abdominal segment. 

 Two salivary glands o])en by a single duct into the oesophagus, and 

 four glands, which probably serve the purpose of a liver, oi)en into the 

 lower end of the stomach . 



The eggs of the flea are small white oval bodies, which, when 

 newly laid, on account of their viscous exterior, adhere to anything 

 with which they may come in contact. 



The ]arva is footless and made up of thirteen nearly equal 

 segments, the anterior of which, the head, is hard, chitinous, and bears 

 the antennae and oral appendages, though eyes are absent. The oral 

 appendages are composed of a pair of conical toothed mandibles, a pair 

 of chitinous maxillae, with a two-jointed pilp attached on each side, 

 and an upper and lower li]>. A small provisional organ, like that on the 



