106 BRITISH TYROGLYPHID^;. 



glyphus was closed by a membrane stretched across, 

 which was ruptured by the first egg that passed ; this, 

 however, is an error. 



The Genital Suckers. These, when present, exactly 

 resemble those of the male, therefore nothing need be 

 said about them beyond what has already been written 

 above respecting those of the male (page 91). In the 

 genus Hericia the ? is without genital suckers. 



THE NERVOUS SYSTEM. Pis. A, figs. 812; C, figs. 



1,3. 



This is extremely difficult to investigate in the 

 Tyroglyphidae, and very little is known about it ; the 

 only writings touching the subject in any serious 

 manner are the paper by Nalepa, so often quoted in 

 this chapter, and my own paper on the brain in 

 Acarina,* of which paper, however, only a small 

 portion refers to the Tyroglyphidae. I have also 

 made some researches for the purpose of this book, 

 but I have not met with the success which I was able 

 to attain in some other families. 



The so-called brain may be fairly well observed in 

 really good sections ; and the four pairs of great nerves 

 to the legs are comparatively easily traced in all 

 Acarina ; but having dealt with these it is most 

 difficult to get further with the nervous system of the 

 Tyroglyphidas with any certainty ; although something 

 may be learned with care and patience by a person 

 well accustomed to the same organs in other families 

 of Acarina where they are better developed ; and 

 something may perhaps fairly be guessed from homo- 

 logy and analogy to those families. 



The great nerve-centre in all Acarina, the so-called 

 brain, consists primitively, no doubt, of a large sub- 

 oesophageal ganglion ; a supra-oesophageal ganglion, 

 usually somewhat smaller ; and a pair of short broad 



* '* On the Form and Proportions of the Brain in the Oribatidse 

 and in some other Acarina," 4 J. B. Micr. Soc., 1895, pp. 274282. 



