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Show 1895.] LUNGS OP SNAKES, AMPHISB^ENIDiE, ETC. 701 doubtless Prof. Cope himself among the first, will admit that the animals represented in (7) pis. xii., xiii., xiv., xv., and xvi., must have been prepared for sketching by cutting through the membranous tissue that connects the alimentary canal with the mid-dorsal line of the liver (aud carries veins from the alimentary canal to tbe liver), and also the membranous tissue which passes to the right of tbe alimentary canal and attaches the liver to the dorsal body-wall and bears other blood-vessels to the liver; and will see that after cutting of these dorsal attachments of the liver that organ has either been merely pushed aside, as in pis. xiii. and xiv., or on the other hand has been turned over bodily through some 180 degrees, as in pis. xii., xv., and xvi. In either case the position of the lung with regard to the liver is not the natural one, and the impression is conveyed that the lung lies more to the left of the median plane than it really does. That the membranes have been cut through, and the liver displaced as described, will, as remarked, be granted by those who have carefully studied this region of the snake's body, because of the unnatural position of the liver; but the displacement with inversion through some 180°, in the case of the snakes figured on plates xv. and xvi., will be recoguized by all who remember that in Snakes, as in other animals, the postcaval vein enters the right half of the liver and not the left. The figures, in fact, are drawn in all good faith and tell their tale truthfully when carefully questioned, but the lettering and their appearance on the face of them are misleading. The most striking figure is that of Charina bottee [I. c. plate xii.] [one of the more normal two-lunged forms], where, after cutting through the dorsal attachments of the liver, the lungs and liver have evidently been turned over together in one piece to the right, so that the lungs lie ventral to the liver, with the larger right lung on the left and described as the left, and the smaller left lung on the right and described as the right. W e may now turn to consider the case of Heterodon platyrhinus [the curious forward diverticulum of whose chief lung has long been known1]. Cope figures this snake in both of his papers (7) pi. xv. and (8) pi. xxviii., and on account of its special interest in another respect I figure part of it here also [PI. X L . fig. 1]. In this snake the position of the rudimentary lung with regard to the other, which is just as represented in Cope's figure, is at first view very deceptive. It will be seen that the smaller rudimentary lung lies ventral to the other and to the right of the trachea. Not only, however, does the position of the larger lung with regard to the other organs, and notably to the blood-vessels above mentioned, prove that larger lung to be the right lung, but sections [see figs. 2-4], showing as they do a corresponding rotatory displacement of the 1 See Duvernoy, 'Lecons d'Anat. comp. de Gr. Cuvier,' 2nd ed. torn. vii. p. 138 (1840). P R O C ZOOL. Soc-1895, No. XLV. 45 |
