HYPODERID^. 229 



CASE That author had also formerly observed, on the inner surface of 

 the skin taken off a common mouse, small milk-white knots of 

 about the size of a pin's head, which, under the microscope 

 turned out to be nests of mites, containing 20 or 30 small mites. 

 He also met with flat angular mites many times larger, under the 

 skin of a fox. Whether both or either of these belong to this genus 

 there are not sufficient materials to determine — nor, indeed, have 

 we met with any carefully described and figured record of the 

 presence of the genus Hypoderas anywhere but under the skin of 

 various species of birds. 



There is no doubt, however, as to a species described by Dr. . 

 Gros, in a paper in the " Bulletin of the Imperial Society of 

 Moscow" (1845, s. 397, tab. 11), which he found under the skin 

 and even in the muscles of a heathcock. Thereafter, in 1864, V. 

 Frauenfeld described a species (Hypoderas unicolor) that was 

 found in great numbers massed together in a ball forming a sub- 

 cutaneous tumour under the wings of a grosbeak (Verh. Zool. 

 Bot. Gesell. in Wien, XIV., 385). 



Since then a considerable number of species have been described 

 and figured by Giebel in the "Zeitschr. Gesamm. Naturw. III.,'* 

 from which we have taken the illustrations of this group. 



Genus Hypoderas {Frauenfeld)^ Cellularia, Montague. 

 Characters same as those of the sub-family. 



No. I. Hypoderas brevis {Gieb.). — 1. Magnified sketch of ditto fi-om GiebeFs 

 figure. 



Hypoderas brevis. Copied from Giebel's figure. 



