90 FISH GALLERY. 



Osteoglossum and Sclerojiages are closely allied genera, the 

 latter with a longer body and with more extended dorsal and 

 anal fins than the former ; in both the mouth-cleft as seen from 

 the side is long and oblique, and the lower jaw is prominent and 

 bears a pair of barbels. Scleropages leichardti (247) is the 

 " Barramunda" of the Rivers of Queensland, although the name 

 is indiscriminately used for this fish and the Ceratodus (171, 

 Wall-case 6) . Another species of Scleropages occurs in Sumatra 

 and Borneo ; Osteoglossum occurs in Brazil and the Guianas. 



Heterotis (248) is a small-mouthed fish common in the Nile, 

 Gambia and other rivers of tropical Africa. The air-bladder is 

 cellular and probably is used as a breathing organ, and there is 

 an accessory respiratory organ, spirally coiled, above the fourth 

 gill arch. During the breeding season the fish constructs a large 

 nest in a part of the swamp where the depth is about two feet, 

 and here it rears the young, which at one period of their 

 development breathe by external gill-filaments. 

 Clupeidse, The Clupeidae are an important family of fishes including the 

 Herrings, Shads and Anchovies ; they are principally coast fishes, 

 widely spread in the temperate and tropical zones, and some of 

 them entering fresh waters communicating with the sea. The 

 dorsal fin is small and set nearly in the middle of the back; there 

 is no adipose dorsal fin. The scales are thin and readily shed ; 

 the gill-opening is usually very wide, and the opercular apparatus 

 is complete. The parietal bones are separated by the supra- 

 occipital; in most cases the maxilla assists the premaxilla in 

 bounding the upper border of the gape; the teeth are feeble 

 (except Chirocentrus), and two surmaxillary bones are usually 

 present. The postclavicle is applied to the outer side of the 

 clavicular bone, and not to the inner side as in the Salnionidse. 

 The pelvic fins have 6-11 fin- rays. The stomach is produced 

 back into a blind sac; the air bladder in some cases (e. g. Herring) 

 opens directly to the exterior in the vicinity of the anus. Inter- 

 muscular bones are numerous ; the ribs are mostly sessile, being 

 inserted behind the transverse processes. The family is well 

 represented in Cretaceous and Tertiary strata. 

 Dorab. The Dorab, Chirocentrus dorab, 253, common in the Indian 

 and Western Pacific Oceans, is a brilliantly silvery fish growing to 



