OCR Text |
Show 1876.] ANATOMY OF CHAUNA DERBIANA. 191 narrow zonary belt of glands. It can, however, be seen that by far the majority of the glands are aggregated into a posteriorly situated patch. The only birds with which I a m acquainted in which the proventricular glands do not form a zone, or an approach to one, are Struthio and Bhea. In the Gallinee and Anseres they form a zone. The glandular surface occupies a subelliptical space, 2 inches by 11 in its long and short diameters, in the upper and back part of the canal, with the long axis in the direction of the tube. Its lower end is 2f inches from the upper orifice of the gizzard. The gland-tubes are simple, not racemose, and average £ inch in length. The remainder of the area of the proventriculus, about five sixths of it, is covered with coarse and irregularly folded epithelium. The gizzard is constructed on the usual type ; it is decidedly small in proportion to the size of the bird (in the Anseres it is as conspicuously large), being much more elongate, narrow, and less muscular than in grain-feeders. Longitudinal folds plicate the triturating surfaces, which are smooth in the Geese, Ducks, and Swans. The spleen is the size of a haricot bean, and of much the same shape. Its position is in no way peculiar; but, as in all birds, being placed above the gizzard, it tends to confirm the opinion that the latter organ is only the representative of the pyloric end of the stomach, the cardiac component of which is represented by the proventriculus. The liver is composed of two simple rounded lobes, united by a narrow isthmus of hepatic tissue; the lobes are of nearly equal size ; and there is a fairly voluminous gall-bladder. The following table gives the intestinal lengths :- o*. 2 ft. in. ft. in. Small intestine 7 3 6 10 Large intestine 1 1 0 7 Caeca 0 3 0 2 The duodenum, with its characteristic bend round the pancreas, is more capacious than the rest of the small intestine; but it is not large, being about | inch in diameter. The hepatic and pancreatic ducts enter it at the bend, 2\ inches from the pylorus. The pair of caca present a condition unlike that found in any other bird with which I a m acquainted. In that they are situated some considerable distance from the cloaca, they agree only with Struthio and Rhea. In the much larger Cassowaries the large intestine is not more than 7 inches long. In both Apteryx and the Tinamous, as well as in all other birds, the Anseres and Gallinee included, the large intestine does not exceed 4 inches in length. Chauna in having a large intestine, the length of which is several times the diameter of the gut, agrees therefore with Struthio and Rhea only. These organs are figured in Plate XIII., they being opened up in fig. 1 to show their internal structure. Instead of being smooth externally, the caeca are sacculated on two longitudinal bands. They are peculiarly capacious for their |