OCR Text |
Show 1889.] CONVOLUTIONS IN BIRDS. 313 There remain, lastly, some unexpected resemblances between the Pelargi and the Diurnal Birds of Prey; the chief connection is formed by the telogyrous character, the mode in which additional loops of the lengthened gut are stowed away, and the tendency to convert some or one of the principal loops into regular spirals. Amongst the Accipitres, the Old-World Vultures especially exhibit striking Ciconiine similarities. As regards the Cathartidse, I have to deplore want of material. One badly preserved specimen of Cathartes atratus differed greatly from the Accipitres in several particulars ; one of the points being the widely open and periccelous second loop, a feature occasionally met with in the Hemiglottides. Whatever may be the value of these resemblances between the Pelargi and Raptores, they are the only points by which the Raptores can be connected with the rest of the Carinatae ; therefore the view of Garrod to let both form part of his order Ciconiiformes, which is adopted by such an authority as Fuerbringer, becomes strengthened. It is advisable to treat the Cathartidae and Accipitres (i. e. the rest of the Raptores diurni, Serpentarius not having been examined) as equivalent groups, and to combine them under the one name Raptores. The Psittaci are distinctly telogyrous; all their five principal loops are closed and alternating ; this, with the presence of a crop, and the absence of functional caeca, are features which occur again together only in the Accipitres. The absolutely vegetable food of the Parrots would sufficiently account for the differences which exist between them and the entirely zoophagous Accipitres. However, this indication of a possible relationship between the Birds of Prey and Parrots is as little binding or satisfactory as other suggestions based upon other organic systems. Parrots are Psittaci, and semi-psittacine forms, either recent or extinct, are unknown. All the remaining Birds, viz. Garrod's Piciformes, Passeriformes, and Cypseliformes (with the addition of the Striges, Musophagidae, and Cuculidae, and after the exclusion of the Psittaci), have collectively been called Coracornithes by Fuerbringer. This I consider a great step in advance. They represent together the higher birds in opposition to those of lower organization, which, from a very broad point of view, can be divided into two equivalent sets : 1, those chiefly terrestrial (all the Plagio- and Periccelous birds, corresponding roughly with Fuerbringer's Alectorornithes-1-Charadriornithes) ; and 2, those chiefly aquatic (all the typically orthoccelous birds=Fuerbringer's Pelargornithes). It is of course self-evident that such a division of the Aves into three great sets can be maintained only on the broadest phylogenetic basis, taking into account solely the fact that their organization gravitates towards three centres. Naturally, there can be nothing surprising in it that birds, which from all their principal points of organization point to one centre, have, owing to change of habits, secondarily assumed characters which are primitive in, and typical of, another centre. Examples of such convergence are the Laridae, iVccipitres, Pelargi, Striges, and possibly the Psittaci. Concerning the " Coracornithes," it would be very difficult to |