1895.] HYDEACHNLD FOUND IK COfiNWALL, 195 



interior of the ring and cause it to look like a disk ; although, of 

 course, it reaUy remains a ring in structure, and the muscles con- 

 tinue to pass through the mass of eggs just as they did through 

 the ring. Thirdly, that thei'e are a considerable number of fine 

 and short contorted tubes, apparently of a glandular nature, 

 surrounding the outer edges of the ovary, the exact course and 

 connections of which it is extremely difficult to make out, which 

 have not been mentioned by former investigators ; they are 

 apparently outgrowths and plications of the peripheral parts of the 

 ring itself, and possibly function as accessory glands. 



The {so-called) Genital Suckers (Plate VIII. fig. 19). 



In some families of Acarina the external genital aperture is 

 accompanied by the organs which are known by the name of 

 " genital suckers." In the Oribatidae and Tyi-oglyphidae they lie 

 actually within the genital opening, and are only exerted when in 

 action or by means of pressure. They are, in these families, soft 

 extensible organs, usually either two or three pairs, and certainly 

 have the appearance of suckers. In the Oribatidae they are of 

 somewhat complicated structures and are the only sucker-like 

 organs on the body. The mode of coition of the Oribatidse is not 

 known ; but these organs have been considered to be genital, i. e. 

 copulative, suckers by Claparede ^, Nicolet ^ and others. In the 

 Tyroglyphidfe they have been considered to fulfil a similar office by 

 Fumose and Eobin ', and Nalepa ' ; but in these creatures the mode 

 of coition is known, and it takes place by a bursa copulatrix at the 

 anal end of the female. The male during coition is above, not 

 below, the female ; so that the supposed copulative suckers of the 

 female cannot possibly touch the male during coition ; and in most 

 species the male only, in addition to these so-called genital suckers, 

 is pro\TLded with a pair of what certainly are copulative suckers, 

 placed near his anal end. These considerations, inter alia, led 

 Megnin '^ to deny entirely that these organs were suckers. He says 

 that he has watched them in action, and that it is at the moment of 

 the deposition of the egg by the female that they are exerted, and 

 that they then guide the egg. Megnin admits that this does not 

 explain their presence in the male ; he says that he has not ever seen 

 them in action in that sex, but he suggests that they probably serve to 

 break the adherence of the male and female after the termination 

 of the coitus. The principal objection to Megnin's view as to the 



1 'British Oribatidae,' by the present author. Eay Soe. 1883, vol. i. pi. F. 

 fig. 11. 



^ "Studien an Acariden," Zeit. wiss. Zool. 1868, p. 511, taf. xxxvii. fig. obb. 



^ " Histoire Naturelle des Acariens qui se trouvent aux environs de Paris " 

 Archiv. du Museum, t. vii. p. 415. 



* " Memoire sur les Acariens des genres Cheyletus, Glycvphagus, et Tyro- 

 glyphus," Joum. de I'Anat. et de la Physiol. (Robin's), 1867, pp. 591-592. 



5 " Die Anatomie der Tyroglyphen," Sitzb. k. k. Akad. Wien, 1885, p. 16. 



8 " Memoire sur les Hypopes," Journ. de I'Anat. et de la Physiol. (Robin's), 

 1874, pp. 239-210. 



13* 



