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Show 314 PROF. HUXLEY ON THE ALECTOROMORPHAE. [May 1 > not difficult to show, from other considerations, that these are really the most important divisions which can be established for the geo graphical distribution of both Birds and Mammals. Thus, in addition to the Alectoropodes, the following important groups of Birds are either confined to the northern area, or are represented elsewhere by not more than one or two species Pteroclidce, Vulturidee, Otididce, Upupidce, Gruidee, Bucerotidce, while, in comparison with the southern area, it is very poor in Ratitee, Psittacomorphce, Peristeromorphce, Caprimulgidce. With respect to Mammals, the northern area is almost coincident with the distribution of the Insectivora, and it is the headquarters of the Ungulata; Catarrhine Apes and Lemurs are confined to it; and it contains only two species of Marsupialia, and very few of Edentata. Among the lower Vertebrata, Ganoid fishes are not found outside this area. To the southern area, on the other hand, are restricted :- The Ratitee (except Struthio). The Tinamomorphee. The Cathartidee. The majority of the Pigeons and Parrots, and all the most peculiar types of both. The Trochilidce and the Aptenodytidee, with few exceptions. Many annectent, or apparently isolated, forms of birds, such as the Palamedeidee, Psophidee, Dicholophidce, Heteromorphce. iVmong Mammals, the Marsupialia are as nearly confined to and coextensive with it, as the Insectivora are in respect of the northern area. The Platyrhine and Arctopithecine Monkeys and the Monotremata are confined to it. It is the headquarters of the Edentata, and is very poor in Ungulata-so as exactly to reverse the characters of the northern area in these respects. In a well-known and very valuable essay on the Geographical Distribution of Birds*, Dr. Sclater divides the surface of the globe primarily into an eastern and a western area, which he terms respectively Paleeogeea and Neogeea. However, if we take into consideration not merely the minor differences on which the species and genera of Birds and Mammals*are often based, but weigh the morphological value of groups, I think it becomes clear that the Nearctic province is really far more closely allied with the Palaearctic than with the Neotropical region, and that the inhabitants of the Indian and the ^Ethiopian regions are much more nearly connected with one another and with those of the Palaearctic region than thev are with those of Australia*?. ^ And if the great frontier line is latitudinal rather than longitu- * Journ. Proc. Linn. Soc. Zool. vol. ii. p. 130. t M . Pucheran has insisted very strongly and, as I think, justly on the esscnl i-,1 unity of the fauna: of Europe. Asia, and Africa. y csscnti.d |
