686 MEDICAL ENTOMOLOGY 



2. Body short ; legs very stout, hind pair reaching much beyond 



the tip of body PteroptU5. 



Body longer ; hind legs not reaching beyond tip of body .... 3 



3. Peritreme on the dorsum, very short; body very distinctly 



constricted . Ptilonyssus. 



Peritreme on venter, longer ; body not distinctly constricted .... 4 



4. Mandibles in both sexes chelate ; parasitic on bats and mice . Liponyssus. 

 Mandibles in male chelate, in female long, styliform, parasitic 



on birds Dermanyssus. 



5. Dorsal shields present ; coxae close together ; living in seals. Halarachne. 

 No dorsal shields ; hind coxae separated from the fore ; living 



in monkeys Pneumonyssus. 



GENUS PTEROPTUS, L. 



The species belonging to this family are all parasitic on bats ; they 

 are remarkable on account of their curious shape. The abdomen is small 

 and round in the female (Plate LXXXVII, fig. 4), and practically absent 

 in the male. The legs, which are short and thick and covered with 

 bristles, are inserted about equal distances apart around the body, so 

 that the mite can walk forwards or sideways with equal facility, and often 

 adopts a crab-like mode of progression. The stigmata are situated on the 

 dorsum, but the peritreme extends round to the ventral surface as shown 

 in the figure. The method of reproduction is peculiar ; the eggs hatch 

 out in the body of the female, and the larva is retained until the nymphal 

 stage is reached. The nymph is just as active as the adult, and also 

 lives on the wing of the bat. Pteroptus vespertilionis (Plate LXXXVII, 

 fig. 4) is common on the yellow bat, Scotophilus kuhli, in Madras. 

 Several allied genera have been described, but they probably represent 

 immature stages of Pteroptus. All the species are blood-suckers. 



GENUS DERMANYSSUS, DUGES 



The species belonging to this genus are all parasitic on birds, the blood 

 of which they suck ; they may be recognized by the following charac- 

 ters : The body is oval and soft and finely striated all over ; the 

 mandibles are different in the two sexes ; in the female they form a long 

 thin stylet, and in the male are chelate. 



Dermanyssus gallinae, Redi, is the common and perhaps the only 

 species ; it is a temporary parasite of poultry, behaving in the same way 

 as Argas persicus ; the mites hide in cracks and crevices in the coops in 

 the poultry yard, and especially in straw in pigeon coops, during the day, 

 and come out at night to feed. Colonies, consisting of males, females 

 and immature stages are found together in their hiding places. They 

 occasionally attack man and may cause considerable cutaneous irritation. 



