OCR Text |
Show 1899.] ON THE ELOOD-VESSELS OP TELEOSTEAN FISHES. 939 3. O n the Relations of the Efferent Branchial Blood-vessels to the " Circulus Cephalicus " in Teleosteau Fishes. By W . G. R I D E W O O D , D.Sc, F.L.S., Lecturer on Biology at St. Mary's Hospital Medical School. [Received August 1, 1899.] (Plates LXIII.-LXY.) INTRODUCTION. When engaged in dissecting a Herring some years ago, I was struck by the fact that the four efferent branchial vessels all reached a median vessel which was continuous behind with the dorsal aorta, and that the circulus cephalicus was situated anteriorly to the first pair of vessels. This condition was so totally different from what I knew to be the arrangement of the vessels in the Cod, that I examined the same parts in a third form, the Salmon, and here found a condition intermediate between the two preceding. The results appeared to warrant a further inquiry, and the present investigation was undertaken with a view to ascertaining what are the commonest, and what the extreme modifications of the efferent branchial arteries to be met with among Teleosteau fishes. The greater part of the work was done during the summer vacation of 1892 at the Marine Laboratory of St. Andrews, Scotland ; but owing to the difficulty of making the series of fishes thoroughly representative, the investigation has been protracted over a period of seven years. Late, however, as it may now appear, I take the opportunity of expressing m y warmest thanks to Prof. W . C. Mcintosh, M.D., F.E.S., for his kindness in placing at my disposal for six weeks during the summer of 1892 all the facilities that are afforded by the St. Andrews Laboratory for the procuring and injecting of the indigenous fishes. I have also to thauk Prof. Cr. B. Howes, LL.D., F.R.S., of the Royal College of Science, London, for specimens of Perca, Trachinus, Lophius, Fistularia, Motella, Ammodytes, Silurus, Exocoetus, Esox, Albula, Megalopis, Chirocentrus, and Hippocampus, and Mr. G*. A. Boulenger, F.R.S., of the Natural History Museum, for specimens of Corvina, Equula, Gobius, Sphyrcena, Hemichromis, Clarias, Saccobranchus, Malapterurus, Gallichthys, Scopjelus, Cobitis, Marcusenius, Balistes, Tetrodon, Orthagoriscus. The series of forms examined includes 61 species belonging to 57 genera. |