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Show 22 MR. A. D. IMMS ON THE GILL-RAKERS [May 3, (5) The short course of the lateral abdominal veins and their fusion anteriorly with the posterior vertebral. (6) The tendency towards a disappearance of a special suprarenal portal system. As to Pygopus, the following points seem to me to be deserving of special notice :- (1) The large number of gastric arteries. (2) The origin of a considerable number of the visceral arteries from the intercostals, and not directly from the aorta. (3) The large number of dorsal parieto-hepatic portals, and the existence of an equal number of portals arising dorsally on the left side and reaching the liver via the stomach. (4) The connection between the branches of the well-developed lateral abdominals and the dorsal parieto-hepatics. (5) The absence, or at most small development, of lateral epigastric veins. (6) The abundant connection (by 8 trunks) of the median epigastric with the liver and its connection anteriorly with the vena cava. (7) The presence, as in Chamceleon, of a posterior vertebral vein continuous with the afferent renal. (8) The opening of a single oviclucal vein into the afferent renal posteriorly, and of a single vein into the ovarian and thence into the caval vein anteriorly. Concerning Tarentola and Phelsuma, there are fewer general observations to offer. But I may direct special attention to the following :- (1) The absence of at least conspicuous lateral epigastrics. (2) The connection of the median epigastric with the vena cava anteriorly. (3) The restriction of the azygos to the right side. (4) The shortness of the lateral abdominals. 3. Notes on the Gill-rakers of the Spoonbill Sturgeon, Polyodon spathula*. By A. D. I m m s , B.Sc. (Lond.), Assistant Demonstrator in Zoology in the University of Birmingham. [Received April 19, 1904.] (Plate II. f ) The gill-rakers of fishes are organs which present a considerable range of variation in form and structure, but which, as yet, have been very inadequately studied. In their most familiar form they * Communicated by Prof. T. W. B r i d g e , F.R.S,, F.Z.S. t For explanation of the Plate, sec p. 34. |
