46 HALF-AN-HOUR 



from the presence of the four pairs of limbs, may be supposed 

 to be adult forms. Much careful work is required to elucidate 

 their life-history. Reference is made by S. J. Mclntire to some 

 observations by J. G. Tatem, reported in a previous part of the 

 same periodical. The Hypopi have a curious habit of drawing 

 up the hinder limbs towards the head, whereby it is often ex- 

 ceedingly difficult even to see them. 



Gamasus from House-Fly. (PI. 24, Figs. 2, 3 4.) — I cannot 

 give the specific name, though familiar with the creature. I 

 find it commoner on small flies of two or three species, 

 frequent on the window-panes in June, than on Musca domestica 

 (the Jiouse-fi}^. The chelate mandibles of these creatures are 

 very remarkable. 



Gamasus coleoptratorum. (PI. 25, Figs, i and 2.) — This is 

 the special parasite of the Dung-beetle {Geotropus stercorarws), 

 and from the length of limb in proportion to the body is probably 

 a male. In some members of the genus, however, the limbs of 

 the second pair are, in this sex, specially modified as powerful 

 prehensile organs. Mr. Atkinson's account (see p. 56) of the 

 readiness shown by the present fellow to " put itself outside 

 other Acari " is vastly amusing. I can confirm the description 

 by my own experience, though my omnivorous capture belonged 

 to a different genus. 



Gamasus from Rat. (PI. 25, Fig. 3.) — This is probably the 

 one figured and described in Sci. Goss. for October, 1868, p. 

 232, as from a Mole, though both representation and account 

 are exceedingly imperfect. We must not be too impatient to 

 give these things names; many of them have -been as yet but 

 very imperfectly investigated. Our object should be to investi- 

 gate structure and life-history minutely and accurately, and to add 

 to knowledge. 



Dermanyssus. — I am familiar with two species of £>er- 

 ma?iyssus, and have others awaiting study. One of those I know, 

 D. gaUiiice^ is at times a great plague to fowl-keepers ; the other, 

 D. aviiwi, is no less an annoyance to those who have pet canaries 

 and other singing-birds. Figures of £>. gallince. will be found in 

 Part 2 of a " Descriptive Catalogue of the New Sydenham 

 Society's Atlas," by the Honorary Secretary, Jonathan Hutchin- 

 son (PI. 4, p. 87) ; in which work are also contained original 

 figures of Itch-Mites from some of the lower animals which 

 occasionally (like D. gallince) wander to man, and give rise to 

 more or less serious affections of the skin. 



TuFFEN West. 



