12 GENEEA OF THE FAMILY. 



"vras the next aiitlior who recognized the Wah'uses as forming a 

 distinct family, which he termed Bosmaridce. In this step, he was 

 immediately followed by Gray,* and by the present writer t in 

 1870. Lilljeborg, J in 1874, also accorded them family rank, as 

 has been the custom of late with various other writers. Gill, 

 in 1872, raised them to the rank of a " superfamily " {Rosma- 

 roidea), treating them as a grou]p co-ordinate in rank with his 

 ^' PJiocoidea,^^ consisting of the Phocidcc and Otariidce. 



Their final resting-place in the natural system has now prob- 

 ably been at last reached, the majority of modern systematists 

 agreeing in according to them the position and rank of a family 

 of the Finnipedia. To Ilhger seems due the credit of first dis- 

 tinctly recognizing the real afiinities of both the Pinnipeds and 

 Sirenians to other mammals, and with him originated the names 

 by which these grouxDS are now commonly recognized, the chief 

 modification of Illiger's arrangement being the reduction of the 

 Pinni])edia from a distinct order to the rank of a suborder of the 

 Ferce. 



GENERA. 



The family Odoha'nidcc {TrichecJiidcv Gray and Brookes = i?06- 

 maridce Gill) includes, so far as at present known, only the 

 existmg genus Odobmius (= Triclieclius of many authors, not of 

 Artedi nor of Linne) and the two extinct genera Trichechodon 

 and Alactherium, recently described from fossil remains found 

 in Belgium. Alactherium,\\ while evidently referable to the Odo- 

 hwrndce, differs quite strikingly from the existing ATabuses. 

 The parts known are the left ramus of the lower jaw, the greater 

 portion of the cranium (the facial portion and teeth only want- 

 ing), several cervical vertebrne, a iDortion of the pelvis, and vari- 

 ous bones of the extremities. The rami of the lower jaw are 

 not anchylosed as in the Walrus, and the dentition is quite dif- 

 ferent from that of Odohceims, that of the lower jaw being I. 2, 

 C. 1, M. 4. The symphysis occupies nearly half of the length 

 of the jaw. Van Beueden describes the skull as resembling in 

 some characters the skull of the Otaries, and in others those of 

 the Morses. The molar teeth he says could not be easily distin- 

 guished from those of the Morse if they were found isolated. ISTo 



* Ann. and Mag. Nat. Hist., 3d ser., vol. xviii, 1866, p. 229. 



tBull. Miis. Comp. ZooL, vol. ii, p. 21. 



t Fauna ofer Sveriges ocli Novges Ryggr., p. 674. 



Arrangement of Families of Mammals, 1872, p. 69. 



II Van Beneden, Ann. Mus. d'Hist. Nat. de Belgique, i, 1877, p. 50. 



