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Show 1 9 0 6 .] RESPIRATORY SYSTEMS IN THE OPHIDIA. 517 It will be remembered that in Python *, contrary to what is found in Eunectes f , and even, though to a less extent, in Boa J, the umbilical vein is represented in the adult by a rudiment only. Nevertheless this rudiment was quite obvious in the several examples in which I sought for, and succeeded in finding, it. I am therefore inclined to regard my inability to find the least trace of such a rudiment in Corallus as evidence that the vein has completely disappeared in that snake. This state of affairs is, however, more like that of Python than of the two Boine genera Eunectes and Boa. The vein running from the front end of the liver to the pericardium showed no indications whatever of a branch. Although in this particular the evidence afforded is rather in favour of the placing of Corallus in the Pythonine subdivision, it has less value in that it is a negative character. The intercostal arteries offer a positive character pointing in the same direction. In Boa, Eun.ectes, and Eryx § the intercostal arteries are apt to arise at widely separated intervals from the aorta, a single branch thus arising running backwards or forwards or both for a considerable distance, and giving off a regular series of branches to the right and left of the dorsal middle line of the body. In Python, on the other hand, as the researches of Jacquart|| and my own observations have shown, the intercostals arise regularly from the main trunk of the aorta. Each artery springs separately from the aorta and divides below into two, one for each side of the body. In Eryx, &c. each artery may leave the aorta separately from the point of its origin. There is but a slight development at most of secondary longitudinal intercostal trunks. Now it is important to record the fact that in these characteristic features Corallus is on the side of Python, and departs equally from the conditions observable in the Boas. I do not venture upon any further details concerning the circulatory organs for the reasons already stated. The position of the viscera in the Ophidia is of importance to note as a means of comparison between various genera and even various species. In the present serpent, which measured 55 inches including the short tail, the liver begins fairly close to the heart, its anterior end being only 2| inches from the apex of the heart. The liver itself presents peculiarities worth noting. It is very long, measuring 124 inches altogether. Of these the last 4 inches belong to a backward extension of one of the two lobes. It is very usual for this lobe to extend back beyond the other lobe among Ophidia, and the proportions vary somewhat in different cases. I have not, however, as yet had the opportunity of dissecting a snake in * Beddarcl, " Contribution to the Anatomy of the Ophidia," P. Z. S. 1906, vol. i. p. 28. I may take this opportunity of recording the fact that Python molurus and P. regius agree with P. sebce in the retention of a similar rudiment, f Beddard, loc. cit. p. 18. X Supra, p. 514. § Beddard, loc. cit. p. 33, and P. Z. S. 1904, vol. ii. p. 109, text-fig. 19. jj Ann. Sci. Nat. (4) vol. iv. |