ITCH MITES. 315 



:ase have a single skin cover, and their contents consist partly of 

 yellow debris made by the mites, and partly of a dry white 

 mealy mass, composed of eggs and shreds of stripped-ofT skin. 

 The body is striated as in the other Sarcoptidse. The embryo 

 and young are orange yellow. 



Section II. — Louse Mites infesting the smaller Mammals. 



Genus Myobia {Clap.). 



The next sections of the Sarcoptidae consist of two tribes, 

 neither of which burrow under the skin, but merely live on it. One 

 of the sections is found on the smaller mammals, and the other 

 confined to birds, both of which again may be further subdivided 

 into genera. Both sections have been by some referred to the 

 genus Dermaleichus, but it will be seen that there are very 

 material differences between them. Of those that live on small 

 mammals (on which we now enter), some have a styliform suck- 

 ing rostrum, and these, no doubt, live by sucking the juices of the 

 skin, while others are provided with minute mandibles, and these 

 must therefore feed by browsing either upon the fur or the skin of 

 their hosts. To the former sort belongs the genus Myobia; to 

 the latter, Listrophorus and Myocoptes. Both sections exhibit 

 remarkable modifications of various parts to suit their special con- 

 ditions of life. 



Nos. Myobia musculi (Pediculus muris musculi) Schrank, (Myobia coarctata, 

 "''^' Heyden).—\2, Magnified sketch of male ; 13. Ditto of female. Both 



taken from figures in Claparede's Studien an Acariden. 



The woodcuts show the form of this species, both young and 

 full grown, and of its mouth and anterior legs. The latter are con- 

 verted into thick stumps, so near the mouth that they may be 

 mistaken for palpi, with a curious flexible twisted clasping appa- 

 ratus at their termination, by which the mite holds on to the 

 hairs of its host. Consequently the species is so transmogrified 

 that it appears only to have six legs ; but the figure of the 



