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Show 524 MR. F. E. BEDDARD ON THE VASCULAR AND [May 1, Coluber guttcitus has a lung which is'slightly different in various ways from the species already described. The tracheal gutter extends a good way down the lung, in fact a little way beyond the point where it ceases to be vascular. This point is 5 inches from the apex of the heart, and rather more than 2 inches after the commencement of the liver. The lung-tissue does not cease abruptly anteriorly, but dies away gradually some little way in front of the heart. Here and further forward the membrane lying between the extremities of the tracheal semirings is of considerable breadth. At about on a level with the apex of the heart there is an aperture in the lung-tissue which leads into a forwardly directed diverticulum of the lung. I could find a minute though decided trace of a second lung arising from the tracheal gutter on a level with the apex of the heart. The lung in Erythrolamprus cesculajni is single, there being only a rudiment of the second lung. This rudiment, however, is distinctly vascular and cellular in appearance, and a branch from the pulmonary artery serves it. It is not, however, more than about | of an inch in length, and communicates with the trachea not by a separate bronchus, but by a round hole in the trachea before the latter ends in the interior of the perfect lung. The complete lung extends headwards beyond the point where the trachea enters it, as in various Snakes and Lizards. This section of the lung has a kind of independence, for it possesses a restricted lumen which is not broadly continuous with that of the lung 1853, pp. 65 & 69) distinguish " Pityophis " catenifer and " P ." melanoleucus by, inter alia, the numerous dorsal blotches of the former and the fewer and larger of the latter. Boulenger does not use this difference, and for the good reason (so far as his own views are concerned) that lie regards as a synonym of C. melanoleticus " Churchillia " or " Pitoyphis " bellona of Baird & Girard (loc. cit. p. 66), which has, like C. catenifer, numerous smallish dorsal blotches, but has the narrow rostral and other characters of C. melanoleticus. The specimen of Coluber described above as " Coluber catenifer var. sayi " is quite obviousty Baird & Girard's Pityophis bellona. It has the additional frontal shield mentioned and figured b}r those authors. In other respects, save colour, it agrees in all the characters that I have just mentioned with my two examples of C. melanoleucus; the subcaudal scales are 55 pairs. The colour is paler than that of my example of C. catenifer, but the pattern is the same. These facts seem to me to support the view (held by Cope and others) that Coluber sayi is a distinct species. And I have further evidence pointing the same way. The arrangement of the tracheal gutter is like that of Coluber catenifer, not of C. melanoleucus. In Coluber melanoleucus (measuring 4*1 inches from snout to cloaca) the liver, 7 f inches long, commences 4 inches away from the apex of the heart. A second specimen showed the same proportion. In an example of Coluber catenifer (36^ inches from snout to cloaca) the liver (7£ inches long) commences 2 inches from the apex of the heart. Finally, in " Coluber catenifer var. sayi" measuring 32 inches from snout to cloaca, the liver (6f inches long) begins 2 inches from apex of heart. To resume- the snake called Coluber sayi by Schlegeland Churchillia bellona by Baird & Girard is not to be confused with either C. melanoleticus or C. catenifer. While the scaling of the head agrees with that of C. melanoleucus, the colour plan is that of C. catenifer. Certain visceral characters also agree with those of C. catenifer rather than C. melanoleucus. We must therefore either fuse all these varieties into one species or distinguish three. The latter course seems to be the more reasonable. But it obviously remains to be determined what are the limits of the species, so far as external characters are concerned. |