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Show 1 9 0 6 .] RESPIRATORY SYSTEMS IN THE OPHIDIA. 5 0 7 At the anterior end of the liver is another equally stout dorsal parieto-hepatic, which also arises by three or four twigs from the parietes. Between these two are smaller affluents which spring from two roots. In every case, these vessels are joined by a branch or branches from the stomach before entering the portal vein. At the extreme anterior end of the liver the portal vein, greatly diminished in calibre, is continuous with a slender vein which runs along the dorsal side of the oesophagus; this vein was traced forward to the front end of the heart, and apparently extends rather further, but I am unable to be exact as to its relationships here. It has, I think, a branch from the parietes very far forward, in which case it conforms in its construction to the other veins from the parietes. It is noted that these dorsal parieto-hepatic veins are not in any way connected together to form a continuous longitudinal vein running along the parietes in the region of the liver or near to it. In the Boidae there is constantly such a development of longitudinal veins in the hepatic region. It is possible to compare the anterior vein, which enters the portal vein in a straight line with it at the extremity of the liver, to a somewhat similar vein which in Varanus enters the anterior tip of the left lobe of the liver *. There are also the usual branches of the epigastric vein concerned with the circulation of the liver. The most anterior of these are two which enter, close together, the oesophageal vein already referred to as joining the portal at the anterior extremity of the liver. Along the course of the liver there are also two liranches from the epigastric, each of which arises from that vein by two or three roots. Finally, at the end of the liver a strong branch joins the epigastric and portal just before the latter reaches the liver. There are some further connections between the epigastric and the portal and anterior abdominal posteriorly; but I have not mapped them accurately. The occurrence of a marked anterior and posterior communication between the epigastric vein and the vessels of the liver appears to be general in the Ophidia. It should be noted that the epigastric branches entering the liver at its middle plunge into the liver-substance, and are not directly connected with the portal vein. (2) Some Notes upon the Anatomy of Boa diviniloqua and B. constrictor t. I have had the opportunity of dissecting two specimens of the former Snake which have recently died in the Menagerie. I am therefore able to make known a few anatomical facts which have not hitherto received much attention. So far as I am aware, this particular species has not been studied up to the present. Some other species have been examined with regard to particular points, * Beddard, P. Z. S. 1906, vol. ii. f For a few notes on anatomy see Hering, Wurttemb. naturw. Jahreshefte, xvi. I860, p. 103. |
