_Bibliography of Edentata._—No general work on the order has been published since that of Rapp (_Anat. Untersuchungen über die Edentaten_, 2d ed. 1852). Among numerous memoirs on special groups the following may be cited:—_Myrmecophagidæ_:—R. Owen, “Anatomy of Great Anteater,” _Trans. Zool. Soc._ vol. iv.; G. Pouchet, _Mém. sur le Grand Fourmilier_, 1874; W. A. Forbes, “Anat. of Great Anteater,” _Proc. Zool. Soc._ 1882, p. 287. _Megatheriidæ_:—R. Owen, _Extinct Gigantic Sloth (Mylodon Robustus)_, 1842; Id., “On the Megatherium,” _Phil. Trans._ 1851-56; J. Leidy, “Extinct Sloth-tribe of North America,” _Smithsonian Contrib. to Knowledge_, vii. 1855; H. Burmeister, _Description de la République Argentine_, t. iii. Mammifères, 1879,—which contains full references to various memoirs by Owen, Gervais, Reinhardt, and others. _Glyptodontidæ_:—Owen, _Catalogue of Fossil Mammals, Mus. Roy. Coll. Surgeons_, 1845; T. H. Huxley, “Osteol. of Glyptodon,” _Phil. Trans._ 1865; H. Burmeister, _Annales del Museo Publico de Buenos Aires_, and _Descript. de la République Argentine_, 1879; H. Gervais and F. Ameghino, _Les Mammifères Fossiles de l’Amérique Méridionale_, Paris, 1880,—which also contains a list of all the S. American Edentates described at that date. _Dasypodidæ_:—J. Murie, “Anatomy of _Tolypeutes_,” _Trans. Linn. Soc._ vol. xxx. 1874; A. H. Garrod, _Proc. Zool. Soc._ 1878. For Placentation of Edentates see W. Turner, _Trans. Roy. Soc. Edin._ xxvii. (1873) p. 72, and _Journ. Anat. and Physiol._ vols. viii. and x.; A. Milne-Edwards, _Ann. Sciences Nat._ [6] viii. p. 1; and for brain, P. Gervais, “Formes cérébrales des Edentés,” _Nouv. Arch. du Muséum_, tom. v.; W. Turner, _Jour. Anatomy_, i. 313 (1867). For the dentition of _Orycteropus_ see O. Thomas, “A Milk Dentition in _Orycteropus_,” _Proc. Roy. Soc._ vol. xlvii. p. 246 (1890). Fuller observations on the mutual relations of the various families are given by W. H. Flower, “On the Mutual Affinities of the Animals composing the Order Edentata,” _Proc. Zool. Soc._ 1882, p. 358. CHAPTER VIII THE ORDERS SIRENIA AND CETACEA _Order_ SIRENIA. The purely aquatic habits and fish-like form of the animals of this order caused them to be formerly confounded with the Cetacea, but a more intimate knowledge of their structure has shown that they really belong to a widely different type of the mammalian class.