182 



PRACTICAL PARASITOLOGY 



are distinguished from one another by the position of the uterus, 

 which in Sarcoptes is terminal, in Notcedres dorsal. Other itch-mites 



of the domestic mam- 

 mals belong to the 

 genera Psoroptes, 

 Gerv., and Chorioptes, 

 Gerv. They inhabit 

 the surface of the 

 skin and are usually 

 found among dry 

 crusts and scales. 

 They occur in large 

 numbers and, for this 

 reason, their sexual 

 characteristics and 



FIG. 94. Notcedres cati (Bering) = Sarcoptes minor, developmental stages 

 Fiirstenb. 100 : 1. Left, female from the dorsal aspect ; r. 



right, male from the ventral aspect. (After Eailliet .) a r e more easily 



studied than those of 

 Sarcoptes. 



Otodectes cynotis (Hering) = Chorioptes 

 auricularum (Eaill.) is found in the outer ear, 

 and especially in the cerumen, of dogs and cats. 



The hair-follicle mites belong to yet another 

 family, Demodex. They inhabit the hair-follicles 

 and sebaceous glands of man and of certain 

 mammals. 



All the forms which have been described are 

 sufficiently small to permit of their examination 

 whole, either in the fresh state or after clearing 

 with glycerine. In order to differentiate between 

 species, however, it is sometimes necessary to 

 isolate the chitinous skeleton and its appendages. 

 This is done by very careful maceration in 

 potassium solution in the manner already de- 

 scribed. 



Linguatulidce. 



The Linguatulide which is most readily ob- 

 tainable in Central Europe is Pentastomum den- 

 ticulatum, Hud., the larval stage of Linguatula 

 rhinaria (Pilger) (fig. 95). It is found chiefly in 

 the liver, lungs, and mesenteric lymphatic glands 

 of herbivorous mammals, and it may occur, though more rarely, in 

 the carnivorse and in man. It is a flat, lancet-shaped parasite, 4 to 



FIG. 95. The so- 

 called Pentastoma den- 

 ticulatum, being the 

 second larval stage of 

 Linguatula rhinaria. 

 20:1. (After Leuckart.) 



