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Show 838 MR. F. E. BEDDARD ON THE [Nov. 17, character recalling the claw on the hand of Archaopteryx; but the same thing exists among the Carinatae. Prof. Parker, in his 'Davis' Lecture delivered at the Society's Gardens on June 18th of the present year, remarked that the Swan is similarly furnished with two claws. Prof. Parker has also mentioned the fact that Chauna is provided with a claw upon the first and second digits of the hand1. Moreover, Bhea has only one. There is one structure, however, which does not seem to be repeated in other birds ; the barbs of the feathers in the Ratitae are disconnected and not united by barbules. It seems, however, to be within the bounds of possibility that this is an acquired character, and due more to degeneration than to the retention of an embryonic structure. In flying birds the barbs of the feathers are united, and the whole feather thus offers a greater resistance to the air, and contributes to sustaining the bird in the air-it acts in fact like a parachute; in running birds such a structure would be useless ; hence it disappears and the condition characteristic of the Ostriches is arrived at. Without pretending to have exhausted the subject, I may point out that the foregoing recapitulation of some recently acquired results, all tend to show that the Struthiones are not so isolated a class of birds as was at one time thought, and that in fact there are hardly any, if, indeed, any characters that absolutely distinguish the Struthiones from other existing birds. In an interesting paper on the " Respiratory Organs of Apteryx" to which reference has already been made, Prof. Huxley draws attention to certain points of resemblance between Crocodiles and birds. " As in birds, the liver lies between the stomach and the pericardium, and has a peculiar peritoneal investment shut off from the great sac of the abdomen ; and, as in the Ostrich, the whole circumference of the stomach is united by fibrous tissue with the parietes," &c. This passage attracted my attention, and I have endeavoured to investigate the stomach, liver, and intestines of other birds with a view of ascertaining whether the Ostrich is really more like the Crocodile than is any other bird in the disposition of its viscera. The result has been to show that the Ostrich, and for the matter of that such of the other Struthiones as I have had the opportunity of studying, are not peculiar in the disposition of their abdominal viscera. In the course of m y studies I have come across other facts in the disposition of the viscera, which appear to me worth recording and which I include in the present paper because they throw some light upon the same series of facts. Prof. W . N. Parker, in a note upon the " Respiratory Organs of Rhea" has incidentally pointed out that in this bird, as in the Ostrich, the abdominal viscera are separated and enclosed in three compartments of the peritoneum ; the right lobe of the liver is shut off from the left lobe, and from the rest of the viscera, into a chamber by itself; a left chamber includes the left lobe of the liver and the gizzard, while the intestines lie in a third chamber situated above as well as behind these two anterior ones. 1 P. Z. S. 1863, p. 515. |
