GENUS HECTOPSYLLA 449 



care which has been taken to isolate affected persons, and probably also 

 to the damp climate of these ports, it has not succeeded in gaining 

 a footing. 



The male and the imimpregnated female behave in the ordinary man- 

 ner of fleas, and feed on the blood of man and many other animals, 

 domestic and wild ; the pig appears to be a favourite host. The female 

 is much more commonly met with than the male. When impregnated 

 she attaches herself to the skin, boring a way in with the mouth parts, 

 and remains stationary in this position for a week or more, while the ova 

 mature. During this period the abdomen becomes enormously distended 

 (Plate LVI, fig. 4), until the body is the size of a small pea, the head 

 and a part of the neck being just visible at one end and the terminal 

 segments of the abdomen at the other. The swelling is accompanied by 

 great stretching of the integument, affecting mainly the middle segments, 

 the anterior ones being pushed forwards and the posterior ones back- 

 wards, so that the wall of the distended portion is chiefly composed of 

 the inter-segmental membrane. When the eggs are mature they are 

 either passed out while the female is fixed to the skin, or the flea may 

 become detached. 



The Jigger usually attacks the skin between the toes, though it is not 

 restricted to this region. The presence of the insect gives rise to some 

 inflammation and swelling, which usually fixes it more firmly in the 

 tissues. In some cases severe disability may result from the inflammatory 

 reaction which follows. 



The life history, so far as it is known, resembles that of other fleas ; 

 the pupa is enclosed in a cocoon. 



Dermatophihis caecata, Enderlein, is a rare or at least a little 

 known species, chiefly of interest because it has been taken on Mus 

 rattiis. The table already given will suffice to distinguish it from 

 penetrans. 



GENUS HECTOPSYLLA, FRAUENFELD. 



This genus contains four species, all American, of which only one, 

 psittaci, Frauenfeld, is at all well known. This species has been intro- 

 duced into aviaries in Europe with birds, especially parrots, imported 

 from South America. The female differs from the other Sarcopsyllidae 

 in having the sternal plates of the second to the seventh segments divided 

 in the middle line ; when the abdomen is distended by the ripening 

 ova the lateral portions of the plates separate from one another, and are 

 conspicuous on the membraneous wall, 

 57 



