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Show 1899.] BLOOD-VESSELS O F TELEOSTEAN FISHES. 941 LITERATURE. On searching through the literature of the subject, one cannot fail to be struck by the fact that the arterial system of Teleostean fishes has been very greatly neglected, and the disposition of the efferent branchial vessels particularly so. Meckel and Hyrtl appear to have been the only anatomists to undertake anything like a systematic study of these latter. Meckel in 1831 (14. p. 192) pointed out that the mesial ends of the third and fourth efferent branchial vessels are usually close together, and may unite with one another before joining the aorta; and he furnished a few observations on the efferent branchial system of Gadus, Trigla, Perca, Pleuronectes, Lophius, and Murcena. Seven years later Hyrtl (7) gave a table showing the proportions of the circulus cephalicus in fourteen species of Teleosteans, supplemented by a considerable amount of information concerning the vessels associated with the circulus, and good figures of the efferent branchial system of Perca, Gadus, and Tinea. Stannius in 1849 (23. pl. v.) published some fairly reliable figures of the efferent vessels of Cyclopterus, Gadus, Salmo, and Scomber, but the blood-vessels were only introduced into his figures to act as landmarks for the recognition of the sympathetic nerves, and must not be treated too critically. In his 'Handbuch' of 1854, however (24. p. 242), he made reference to the fact that the circulus cephalicus is wide in Gadus and Lota, where all the efferent branchial vessels open into it, whereas it is narrow in Scomber and Salmo, in which genera the last two open directly into the aorta. The only other information on the subject is that conveyed by the figures of the Carp by Duveruey (6. pl. ix. figs. 17 and 18), the Perch by Laurillard in Cuvier's ' Histoire Nat. des Poissons' (5. pl. vii. fig. 1), the Cod by Muller (16. pl. iii. fig. 13), the Trout by Vogt (1. pl. L. fig. 2), the Pike by Maurer (13. pl. xi. fig. 1), the Cod by T. J. Parker (20. p. 117), and the contributions by Hyrtl on Heterotis (9), Gymnarchus (11), Chanos (12), and other genera. GENERAL PART. As may be gathered from the title, the observations recorded in this paper concern the efferent branchial vessels and the vessels formed by their confluence. The cceliaco-mesenteric and subclavian arteries usually arise in relation with the hinder part of the circulus cephalicus, or with that part of the aorta which receives the third and fourth efferent branchial vessels. The positions of these arteries are indicated in the figures, and occasional references are made to them in the text; but the investigation does not profess to deal exhaustively with these vessels, nor with the hyoidean, anterior carotid and posterior carotid arteries, which also are associated with tbe circulus cephalicus. The dotted lines in the figures signify that owing to the failure of tbe injection-mass to pass, or owing to the small size of the fish PROC. ZOOL. Soc-1899, No. LXI. 61 |