94 BRITISH TYROGLYPHID.E. 



and Sarcoptidse is perfectly well known; both of these 

 families possess the genital suckers, but in them coition 

 does not take place by the vulva of the $ , but by a 

 special bursa copulatrix at the posterior end of the 

 female ; the male during the act is above, not below the 

 $ , and the ventral surface of the < is turned to the 

 dorsal surface of the $ ; the ventral surface of the ? is 

 next the ground, so that it is quite impossible that the 

 so-called genital suckers of the female can ever touch 

 the $ during the coitus, yet they are as well developed 

 as those of the c? , and are evidently functional. 



SECONDLY, that the males only of the Tyroglyphidas 

 and the Sarcoptidse usually possess a pair of organs on 

 the ventral surface, one on each side of the anus, 

 which all acarologists agree are manifestly copulatory 

 suckers, and which ordinarily bear that, name ; it is 

 perfectly easy to see during the coitus that the $ is 

 attached by these organs, and in many species, par- 

 ticularly of the Sarcoptidse, the coitus continues for a 

 long time ; then in most Sarcoptidae the two sexes, 

 after the first adhesion, have their anterior ends turned 

 in opposite directions and the genital suckers of each 

 sex are far from the body of the other sex, so that 

 they could not act as holding- suckers. In these cases 

 it is easy to see that the attachment is maintained by 

 the copulative (anal) suckers of the male, aided some- 

 times by the interlocking of the posterior legs. In 

 the genus Tyroglijphus and one or two other genera, 

 the males only have a pair of tubercles on the inner 

 side of the tarsus of each fourth leg, which no doubt 

 serve as holding- suckers to maintain a grasp. 

 The principal difficulties in adopting Megnin's view 

 appear to be 



FIESTLY, the apparent improbability that precisely 

 similar organs in the two sexes of the same species, 

 should have such very different functions as he 

 suggests. 



SECONDLY, that the Oribatidas have these so-called 

 genital suckers highly developed ; but in this family 



