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Show 330 DR. GADOW ON THE ANATOMY OF PTEROCLES. [Mar. 21, rhaptes lays four, which in general appearance and so-called structure resemble those of certain Partridges. The Plovers lay the same number. The Pigeons, on the other hand, invariably lay only two ; and this is so characteristic of the whole group that Bonaparte named them Bipositores. Again, all the true Gallinaceous birds produce a great and indefinite number of eggs. Therefore in this respect the Sand-Grouse are more nearly allied to the Plovers than either to Grouse or Pigeons. According to an observation made in the Zoological Gardens of London in August 1865, the period of hatching seems to be a little more than three weeks : two eggs were laid at the beginning of August; and the young birds came out on the 29th of the same month. But one of the most valuable points, as regards the systematic position of the Pterocletes, is the fact that the young when hatched are thickly covered with hairy down, and that as soon as their plumage has dried they are able to leave the nest and seek their food. This removes them far from the Pigeons, which are the most decided pa?dotrophic or gymnogenous of all the birds we know. Now to sum up. W e have seen that there are many points in which the Pteroclida? have striking resemblances to the Columbida? ; but there are also many points in which they approach the Rasores; and it is difficult, if not impossible, to made out which characters are the more important. Prof. Parker was the first to point out clearly that there is a relationship between Sand-Grouse and Plovers ; and Prof. Garrod, in his classification of birds, groups the Columba?, including Pteroclida?, and the Limicola?, including Charadriida?, together under his order Charadriiformes. But the Columbida? undoubtedly are related to the Rasores through such forms as the Cracida? (Peristeropodes, Huxley) and the Tetraonida?; and, in addition, they are linked together by Pterocles and Syrrhaptes. These circumstances.show that there exists a close relationship between Rasores, Columba?, Pterocletes, and Limicola?. Phylogenetic tables as a rule are faulty from being highly hypothetical, and from the imagination being frequently drawn upon in their compilation. However, they can be useful, even if they only show where our knowledge is yet insufficient, or why systems hitherto made do not agree with more recent ideas. Therefore I venture to draw the outlines of a branch of the avian stock, not led by preconceived ideas, but solely guided by the consideration of facts we know, or at least we have a certain right to believe we know. 1. Rasores, Columba?, and Limicola? are nearer related to one another than to the rest of the birds. 2. If the Columba? approach nearer to the Charadrii than to the Rasores, we can express this idea by a stock which gives off two main branches :-one for the Rasores ; and another one which again soon divides into two-one Columbine, and one for the Plovers (see fig. 8). 3. As the Pigeons have closer affinities to the Fowls than the latter have to the Plovers, the Pigeons must be represented by the middle branch, that to the extreme left remaining for the Plovers. |