Yolk-sac, [20]
Zalophus gillespiei, ileo-colic junction and cæcum of, [212]
Zona pellucida, [19]
FOOTNOTES:
[1] In the embryos of reptiles, birds and mammals folds of the somatopleure arise externally to the constricting furrows by means of which the embryo is gradually separated from the yolk-sac, with the resulting formation of the intestinal and abdominal walls. These folds, situated at the head, tail and on the sides, grow upwards and finally meet and unite to form a membranous sac called the amnion. Hence these higher vertebrates (reptiles, birds and mammals) are called Amniota, in contradistinction to fishes and amphibia who have no amnion and are hence known as Anamnia.
[2] The student should not be confused by the fact that a considerable portion of the pancreatic gland in the cat will be found included between the layers of the great omentum, extending over to the left side of the abdomen. This circumstance will be found of importance in studying the development of the dorsal mesogastrium and of the structures connected with it. For the present attention should only be given to the right extremity or head of the pancreas, situated close to the duodenum and included between the layers of the mesoduodenum.
[3] For full details of the anatomical and pathological conditions involved consult B. G. A. Moynihan “On Retro-peritoneal Hernia”—London, 1899.
[4] Iankelowitz, Arch. f. Mikr. Anat., Bd. 46, 1895.
[5] Iguana tuberculata, one of the large lizards native of South America. This animal forms an excellent object for the comparative study of the visceral and vascular anatomy of the abdomen. It possesses a well-differentiated intestinal tract, several coils of small intestine, a well-marked cæcum and large intestine. The examination of this or a similar reptilian form is to be highly recommended. Iguana is easily obtained in any of our large cities, as a considerable number of these animals are annually imported from Mexico and the South American states.
[6] I am indebted to Dr. J. A. Blake, former Assistant Demonstrator of Anatomy at Columbia University, for the valuable suggestion which led to the preparation of [Figs. 276], [277] and [278] together with the correlated text.