INTERNAL ANAT6MY. 97 



otlier acarologists still continued to imagine that 

 coition in the Tyroglyphidae took place by the vulva. 



Megnin * saw that this was not correct ; he recognised 

 the posterior position of the male organ during the 

 coitus, and in practically all his numerous and valuable 

 works he asserts that coition takes place in all Acarina 

 by the anus, which he calls " la fente vulvo-anale, ou 

 1'ouverture ano-vulvaire," and which he considers to 

 be a cloaca. No one can always avoid error ; and even 

 Megnin, who has contributed so largely and so cor- 

 rectly to our knowledge of the Mites, made a double 

 mistake in this ; firstly, coition in the Tyroglyphidge 

 and Sarcoptidae and other Acari where the female is 

 fertilised at the posterior end of the body, is not by 

 the anal opening, but by a special bursa copiilatrix 

 near to it ; secondly, no general rule can be laid 

 down for all Acarina ; the method and the position of 

 the organs vary even within the limits of the same 

 family ; thus in a large number, but not all, of the 

 Gramasidae there is not any real coitus; the female 

 being fertilised by means of spermatophores or sper- 

 matocysts applied by the mandibles of the male ; t and 

 in the Ixodidse the position, where it is known, is 

 totally different from what it is in the Tyroglyphidse ; 

 and Koenike J has pointed out some very curious 

 arrangements in the Hydrachnidse. Kramer, subse- 

 quent to his opinions above recorded, discovered the 

 retro-anal position of the bursa copulatrix in Derma- 

 leichus stilifer Buchholtz, one of the Sarcoptidae ; he 

 imagined this to be a first discovery. The correct 

 position of the bursa was of course fully recognised 

 by Nalepa; it was also stated by Haller.|| 



* ' Les Parasites, etc.,' pp. 219, 220, and numerous other works. 



\ Michael, " On the Variations in Internal Anatomy of the Gama- 

 sidse, especially in that of the Genital Organs, and on their Mode of 

 Coition," 1892, in ' Trans. Linn. Soc. Zool.,' vol. v, pt. 9, pp. 281324. 



" Seltsame Begattung unter den Hydrachniden," in ' Zool. Anz.,' 

 1.891, No. 369. 



" Ueber Milben," 1881, in ' Z. ges. Naturw.,' Bd. liv, pp. 15. 



j| ' Zur Kenntniss,' etc., p. 287. 



