| OCR Text |
Show 946 DR. W. G. RIDEWOOD ON THE [NOV. 28, fall definitely into the one or the other subgroup. Without this subdivision,' such remarkably different forms as Anarrhichas (fig. 23) and Trigla (fig. 28) would come under the same heading. CLASSIFICATION OF THE GENERA EXAMINED. Group A. The first efferent branchial vessel opens into the circulus cephalicus, but the second does not. Subgroup a. The third and fourth vessels open into the median aorta separately.-Engraulis (fig. 1). Subgroup b. The third and fourth vessels open into the median aorta together.-Clupea (fig. 2), Ammodytes (fig. 3). Subgroup c. The third and fourth vessels on each side unite to form a common trunk, which reaches the aorta some distance behind the second vessel.- Chirocentrus, Megalopis (fig. 4). Subgroup d. The third and fourth vessels on each side unite to form a common trunk, which reaches the median aorta immediately behind the second vessel.- Balistes (fig. 5). Group B. The first and second efferent branchial vessels open into the circulus cephalicus, and the third and fourth into the median aorta at some distance behind the circulus. Subgroup a. The third and fourth vessels open into the aorta together.-Scomber (fig. 6), Hgpophtlialmichthgs, Salmo (fig. 7), Coregonus. Subgroup b. The third and fourth vessels unite before opening into the aorta, the common stem being transverse to the length of the body.-Mugil (fig. 8), Hippoglossus (fig. 9), Pleuronectes, Osmerus (fig. 10), Albida (fig. 11). Subgroup c. The third and fourth vessels unite, the common stem sloping backwards towards the aorta.- Malapterurus (fig. 12), Scopelus, Cyprinus (fig. 13), Cobitis (fig. 14), Esox (fig. 15), Marcusenius, Anguilla (fig. 16). Group C. The first and second efferent branchial A-essels open into the circulus cephalicus, and the third and fourth into the aorta immediately behind the circulus. Subgroup a. The third and fourth vessels open into the aorta together.-Labrax (fig. 17), Liocassis (fig. 18), Callichthys (fig. 19), Clarias (fig. 20). Subgroup b. The third and fourth vessels unite before opening into the aorta, the common stem being transverse to the length of the body.-Perca (fig. 21), |
