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Show 1895.] HYDBACHNID POUND IN COENWALL. 195 interior of the ring and cause it to look like a disk; although, of course, it really remains a ring in structure, and the muscles continue to pass through the mass of eggs just as they did through the ring. Thirdly, that there 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 Tyroglyphidae 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 structure1, and are the only sucker-like organs on the body. The mode of coition of the Oribatidae is not known; but these organs have been considered to be genital, i. e. copulative, suckers by Claparede2, Nicolet3, and others. In the Tyroglyphidae they have been considered to fulfil a similar office by Fumose and Eobini, and JNalepa 5; 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 provided with a pair of what certainly are copulative suckers, placed near his anal end. These considerations, inter alia, led Megnin 6 to deny entirely that these organs were suckers. H e 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. Bay Soc. 1883, vol. i. pi. F. fig. 11. 2 "Studien an Acariden," Zeit. wiss. Zool. 1868, p. 511, taf. xxxvii. fig. bbb. 3 " Histoire Naturelle des Acariens qui se trouvent aux environs de Paris " Archiv. du Museum, t. vii. p. 415. 4 " Memoire sur les Acariens des genres Cheyletus, Glyciphagus, et Tyro-glyphus," Journ. de l'Anat. et de la Physiol. (Eobin's), 1867, pp. 591-592. 5 " Die Anatomie der Tyroglyphen," Sitzb. k. k. Akad. Wien, 1885, p. 16. 6 "Memoire sur les Hypopes," Journ. de l'Anat. et de la Physiol. (Robin's), 1874, pp. 239-240. |
