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Show 1903.] ANATOMY OF THE JAPANESE SALAMANDER. 313 parietes side by side in a symmetrically paired fashion. It will be seen that this account does not exactly agree with that of Osawa. I saw only four intercostal veins, which are disposed singly. Two of them lie at intervals from each other in front of the first of the intercostal arteries; then follow two arteries; after this the third vein ; then a pair of arteries, and finally the last of the intercostal veins. Arterice comites aortce *.-The unpaired dorsal aorta for some little distance before and after the origin of the subclavians is accompanied, as shown in the drawing (text-fig. 34, p. 314), by a slender aorta on each side, not distant more than 2 or 3 millimetres from the aortic trunk. At the origin of the subclavians these vessels each give off a branch which accompanies in the same way its own subclavian. These two vessels arise from the aortic trunk between the union of the two aortaa to form the dorsal aorta and the origin of the subclavians, but much nearer to the latter. Each of these vessels, immediately after its origin, gives off a forwardly-running trunk which accompanies the aorta on each side for a little distance, and is lost among the muscles of the back. The main branches run posteriorly and end upon the transverse membrane which ties the transversely-running portion of the oviduct to the parietes. Osawa does not appear to have studied these arteries. Each arteria comes aortce is reinforced during its course by other branches arising from the aorta. That of the left side has two such supplementary roots. One springs from the aorta just in front of the origin of the subclavian; it crosses over (really, of course, below) the subclavian, and runs for a considerable distance alongside of the first branch before joining it. A second branch springs from the aorta on the posterior side of the subclavian. This also runs alongside of the two above-mentioned vessels for a, considerable distance before joining them. The left-hand vessel has only the first of the two accessory blanches, which arises actually from the posterior margin of the subclavian. About halfway between this point and the oviducal mesentery the artery divides into two branches, of which the inner spreads out over that mesentery, while the outer ends in a projecting reddish body which is dealt with later (p. 315). The anatomy of this region of the body in Megalobatrachus is in several respects by no means unsuggestive of the mammalian diaphragm, or, to be more accurate, a portion of the diaphragm. which is itself a complex structure. The transverse position of the membrane supporting the end of the oviduct (found, it must be remembered, in both sexes) is the first notable fact to be pointed out. Secondly, the heart and a great part of the lungs lie in front of this transverse septum, which from its position delimits a "chest" not incomparable with the mammalian thorax. The arteries, which have just been described as ramifying upon the * These arteries must not be confused with the deep-running vertebral arteries figured by Hyrtl and just referred to by myself (p. 310). |
