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Show 116 MR. F. E. BEDDARD ON THE [May 17, gives off at least one branch to the rectum. A little further forward each vein certainly divides into two branches. These branches are, on each side, a renal afferent and a component of the anterior abdominal vein. Both afferent renals receive, as usual, branches from the dorsal parietes. The two roots of the anterior abdominal vein are unequal in size, that of the right hand being considerably the less. It is important to note this fact, since in Eryx conicus the left root of the anterior abdominal vein is the only one which persists. The epigastric vein arises from the anterior abdominal shortly after the junction of its two roots. Eryx johni agrees with E. jaculus. It is a peculiarity of Snakes as contrasted with Lizards, that the anterior abdominal is occasionally partly double, whereas in Lizards it is single after the fusion of its two roots. In the Colubrine and Yiperine snakes, so far as my experience goes, the anterior abdominal is usually single except at its extreme posterior end. In Zamenis gemonensis the vein bifurcates posteriorly, and after a very short course ends in minute branches in the fat-body. In Causus rhombeatus the extent of the bifurcate region of the anterior abdominal is not much greater ; for 8 inches intervene between the opening of the anterior abdominal into the portal and its bifurcation posteriorly, which is 2| inches from the vent. In Boa constrictor, on the other hand, there are 23 inches between the vent and the fusion of the two anterior abdominals anteriorly, which point is 10 inches behind the liver, and therefore less from the point of union of anterior abdominal and portal *. . In the Anaconda the double character of the anterior abdominal vein has been already referred to. In one specimen of Eryx conicus it was single throughout. In another it was partly double, as was also the case with two individuals of Eryx jaculus. In Python sebce (where it is figured as partly double by Jacquart +) the fluctuation of this vein between the single and double condition was more plainly seen. Just in front of the gall-bladder the vessel communicates with the gastric portal vein ; from this point to two inches behind the gall-bladder it is single. Then for a distance of 4| inches it is formed of two tubes lying side by side; these reunite, and finally again separate to form two tubes. In Eryx johni the vein appears to be single after the union of its two posterior roots. Jacquart figures a somewhat different state of affairs in Python. The anterior abdominal bifurcates posteriorly and communicates with only one afferent renal directly as in the Anaconda. The other branch only communicates indirectly (by means of small veins) with the left renal afferent. Hochstetter J observes that in Tropidonotus natrix and Coluber cesculapii there is no direct connection between the abdominal and the renal afferent veins. I can quite confirm this by the conditions observable in Zamenis * I did not ascertain this measurement. t Ann. Sci. Nat. (4) vi. p. 321. J Morph. Jahrh. xix. p. 489. |
