| OCR Text |
Show 844 ON THE VISCERAL ANATOMY OF BIRDS. [No^ /, adherent to the walls of the gizzard ; the horizont septum is «ontl" nuous at the sides with the oblique septum ; it bears a second bloodvessel, which enters the left lobe of the liver, and is fully as large as the vessel on the right side of the body. It appears to me to be permissible to compare these two abdominal veins with the twc.that are found in the Crocodile figured in the drawing (fig. 1, p. 840). In no other birds that I have dissected have I been able to find more than a single "umbilical" or anterior abdominal vein which passes along the falciform ligament to the liver. The lobes of the liver are contained in two separate cavities floored by the horizontal septum, but which are not cut off from the abdomen posteriorly by a membranous band, as they are for example in Bucorvus. Each lobe of the liver is firmly attached to the vertical septum, and by a special membranous band to the oblique septum. The gizzard does not appear to be enclosed in a special sac as in other birds; the horizontal septum covers it above (ventrally), but dorsally there appeared to be no trace of any covering of fibrous tissue, the gizzard projecting freely into the cavity which contains the intestines. In other birds this horizontal septum is not developed or not developed to so conspicuous an extent as in the types already referred to. It is absent, for instance, in the Strigidae, judging, at least, from examples of three species belonging to this family which I have had the opportunity of dissecting. In Pulsatrix torquata, Syrnium aluco and Strix fiammea there is no trace of the horizontal septum, except that in all, the gizzard is enclosed in a special sac of peritoneum, and is firmly attached to the parietes, as mentioned by Owen in his ' Comparative Anatomy' \ In Carpophaga anea there is no horizontal septum, nor in Phasianus ellioti (young). Bhynchotus rufescens agrees with the last-mentioned types in having no horizontal septum ; the gizzard, however, is firmly attached to the left oblique septum, and is enclosed in a delicate but unmistakable peritoneal sac, as in Phasianus. It is interesting to note that in these structural features the Tinamou is totally unlike the Struthious birds. In a subsequent paper I hope to be able to extend these observations to a larger series of birds. I do not wish to deduce any classificatory results from the facts contained in the present paper, which may perhaps be done later ; the main result has been to show that the Ostrich tribe are not more " Crocodilian " in the characters of their abdominal viscera than many other birds. The}* agree, in fact, very closely with the Cranes and Storks and other birds. In addition to the points of resemblance between Crocodiles and birds indicated by Prof. Huxley, the large "omentum" which covers the intestinal coils in the Reptile evidently corresponds with the omentum (pseudepiploon, Weldon) of the Struthiones, Grallatores, &c. 1 Vol. ii. p. 163. |
