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Show 340 MR. E. B. BEDDARD ON THE [Feb. 1C, specimen. In this, however, the first 11 intercostals pierced the body-wall to the left of the middle line, after which the alternate and occasionally paired arrangement began. The greater distance from each other of the anterior set of intercostals, and the fact that they enter the body on the left side, seem to be distinctive features in this Snake, as in some others. Visceral Branches of the Common Aorta.-For the first part of its course the aorta gives off a considerable number of minute branches to the oesophagus and to the liver. Passing backwards these gradually grow in importance. They repeatedly branch, the blanches become fused so that one may almost speak of a longitudinal system running in the mesentery attached to the liver. The first of the particularly strong branches arises opposite to the eighth of the intercostal branches of the aorta, and also opposite to the posterior end of the liver. The vessel differs from the preceding ones in the fact that it supplies the walls of the alimentary tract and only sends a small branch to the liver, and also apparently to the walls of the large blood-vessels entering the liver; it is thus, so to speak, the first of a new series of branches. The next of these vessels arises 32 m m . further on ; it appears to supply the stomach exclusively. The method in which its twigs are distributed to the stomach is as follows:-The vessel when it has reached the stomach immediately bends backwards and runs along the stomach, becoming continuous with the next visceral branch of the aorta. Side branchlets are given off from this common longitudinal trunk. The next visceral vessel arises just opposite to the gall-bladder; when it has arrived at the stomach it divides into three branches. One of these has been already referred to as joining, or rather as in ending in, the previous gastric branch of the aorta; the second branch runs along the surface of the stomach on the opposite side, while the third and shortest branch supplies at least the gall-bladder. The next branch, the superior mesenteric, arises from the aorta 28 m m . beyond the origin of the gastro-splenic. It runs to the stomach in close connection with a vessel from the parietes to the portal vein. Just before reaching the stomach this artery divides into two branches which run in the same straight line ; but one is directed forwards, the other backwards along the surface of the gut; the latter runs along the intestine in close association with the portal vein, gives off branches, and finally returns to the aorta, being continuous with the inferior mesenteric artery. In a second specimen (a male) the gastric arteries are a little different-superficially, at any rate, if not essentially. The last artery occupies precisely the same position, reaching the gut just at the gall-bladder. Although the snake is a rather smaller one, the interval between the gall-bladder and the end of* the liver is greater than in the larger snake, about 5 inches to 4 inches. Corresponding to this is a larger number of gastric arteries lying behind the liver. I counted six of them. Each is, with the exception of the third and the sixth, accompanied by an intercostal |
