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 supra- 

 renal 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 Chammleon, of a posterior vertebral 

 vein continuous with the afferent renal. 



(8) The opening of a single oviducal 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 spatlmla*. By A. D. Imms, B.Sc. (Lond.), 

 Assistant Demonstrator in Zoology in the University 

 of Birmingham. 



[Received April 19, 1904.J 

 (Plate II. t) 



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. Bridge, F.R.S., F.Z.S. 



t For explanation of the Plate, see p. 34. 



