118 BRITISH TYROGLYPHID^:. 



subject of respiration were it not that Pagenstecher 

 mistook the opening of the expulsory vesicle for a 

 stigma, and Turpin and Fiirstenberg mistook the vesicle 

 itself for an air-sack.* Megnin, however, says f that 

 in Gltjcyphacjus spinipes and G. domesticus he found the 

 stigmata at the base of the first pair of legs, and that 

 they were long-shaped slits each protected by a plumose 

 hair and bordered by thick lips. I do not know what 

 the organs were that Megnin saw; I am not aware 

 that any subsequent acarologist has observed them, 

 and it appears to be certain that neither these creatures 

 nor any other known members of the family possess 

 any tracheae or air-sacks. 



MUSCTJLATION. 



PL C, figs. 1, 2, 3, 6, 7, 9. 



This would not be the proper place for entering into 

 an exhaustive account of the musculation of the Tyro- 

 glyphidse; which would necessarily be lengthy, and 

 would probably be of comparatively little interest to 

 most readers. Certain groups of muscles have neces- 

 sarily been described in the foregoing parts of this 

 chapter, e. g. those of the pharynx ; but something 

 may fairly be said to indicate the nature of some of 

 the principal groups of muscles which have not been 

 dealt with in the earlier pages of this work. 



Very little has been published upon the musculation 

 of the Tyroglyphidae ; Nalepa's paper, so often referred 

 to in this chapter, is practically the only study of any 

 importance on the subject ; it is excellent, but is con- 

 fined to a single species, Carpoglyphm anonymus, as 

 the musculation is not treated of in the first part of 

 the paper, which refers to Tyroglyplim longior ; but 

 something exists as to the musculation of some other 

 Acari, as, for instance, Kramer's paper on Halarachne 



* See this book, p. 116. 



f In ' C. R. Ac. Sci.,' 1886, t. ciii, pp. 12761278. 



