BONY FISHES AND GANOIDS. 487 



forms being entirely carnivorous, whereas others are as distinctly vegetable 

 feeders. Most are relatively small fishes, although the balti of the Nile, 

 which belongs to Chromis, grows to twenty inches. Of the genera, Mroplus 

 is Indian, Ghromis and Hemichromis are African and Syrian, and Paretroplus 

 Malagasy. 



SUB-ORDER II. LOPHOBRANCHII. 



This and the following sub-order include a small number of peculiar fishes 

 which may probably be regarded as highly specialised offshoots from the 

 primitive stock of the Acanthopterygii, neither of them having a duct to the 

 air-bladder. The Lophobranchii take their name from the form of the gills, 

 which consist of small rounded tufts arising from the gill-arches ; the gill- 

 apertures being small, and the operculum or gill-cover comprising only a 

 single plate-like bone. All these fishes have the body enclosed in a many- 

 jointed shield of bone, and the mouth is produced into a toothless tube. 

 Another peculiarity is to be found in the exceedingly feeble development of 

 the muscles. 



The first family of the sub-order is formed solely by the members of the 

 genus Solenostoma, which are few in number and small in size, and inhabit 

 the Indian Ocean. These fishes have the fins well de- 

 veloped, no soft rays to the first dorsal, wide gill-apertures, Family Soleno- 

 and the muzzle greatly elongated. The body is much com- stomatidce. 

 pressed and the tail very short ; the soft dorsal and anal fins 

 arising opposite one another from elevations of the hinder part of the body, 

 while the pelvic pair, which are seven-rayed, are situated below the first 

 dorsal, and in the female are united to the chest by their outer edges to form 

 a receptacle for the eggs. None of these fishes have an air-bladder. 



The second family of the group is represented by the pipe-fishes (Syngtia- 

 thus, Siplioiwstoma, etc.), and the still more bizarre sea-horses (Hippocampus 

 and Phyllopteryx), the latter differing from the former in hav- 

 ing the tail prehensile, and employing it as an anchor. These Family 

 fishes are distinguished from the first family by the aperture Syngnathidce. 

 of the gill-chamber being reduced to a very minute opening 

 at the hinder upper angle of the operculum, and by the loss of the first 

 dorsal and pelvic fins. In certain cases some of the other fins are likewise 

 aborted. The pipe-fishes have the body exceedingly elongated, whereas in 

 the sea-horses it is shorter and deeper, while spiny leaf -like processes arise 

 from the ridges on the head and back. Many of these fish have special 

 structural modifications for the purpose of protecting the eggs, as is also the 

 case with some of the Solenostomatidce. Thus, the females of Solenostoma 

 are provided on the lower surface of 

 the body with a roomy pouch, formed 

 by the adherence of the pelvic fins to 

 the skin of the abdomen. The inner 

 walls of this pouch are furnished with 

 long filaments, which aid in keeping 

 the egg in position ; and it is probable 

 that after the fry are hatched they are 

 retained for some time by attachment Fig. 18. PIPE-FISH. 

 to the walls of the chamber. In the 



typical pipe-fishes (Syngnathus) the care of the family falls to the share of the 

 males, which are provided with a long pouch on the under surface of the tail, 



