482 



PISCES—SUB-CLASS III.—TELEOSTOMI. 



Section Centris- 



ciformes. — 



Family 



Centriscidce, 



Section Gobioe- 



sociformes.^ 



Family 



OoiioesocidcE. 



are developed. The first dorsal-fin may either be wanting or composed 

 of a few feeble isolated spines. The backbone contains a very large number 

 of joints, and presents the peculiarity that many of those at the front end 

 are united together to form a solid tube. The fiute-mouths are confined to 

 the warmer temperate and tropical seas. In spite of their large dimensions 

 — their length being frequently as much as from four to six feet — they can 

 only be regarded as highly developed stiokle-backs. 



We now come to the first of three sectional groups, each of which is repre- 

 sented only by one family. The first section is characterised by the presence 

 of two dorsal fins, of which the spinous is very short, whereas 

 the soft one — like the anal — is of moderate length. Of more 

 importance is the fact that the pelvic fins are truly ab- 

 doininal, and have no sort of connection with the pectoral 

 girdle. These fish constitute the two genera Geidriscus and 

 Amphisile; one species of the former being popularly known 

 as the bellows-fish or trumpeter-fish. They are small, short-bodied fishes, with 

 a tubular mouth similar to that of the AulostomatidUE ; and as their powers of 

 swimming are of the very feeblest, they are often carried by currents far out 

 to sea, although their proper haunts are the shallows. 



Although the members of this section and family are likewise of small size, 

 they diiTer from the last in the more normal conformation of their mouths 

 and bodies. Having no spiny dorsal-fin, these fishes are 

 easily recognised by the possession of a sucker on the lower 

 surface of the body, placed between the pelvic fins, which 

 are nearly jugular in position. Both the soft dorsal and 

 anal fins are situated on the caudal region of the body, and 

 are of small or medium extent. There are numerous genera 

 of sucker-fishes, such as the West Indian and South American Gobioesox, the 

 European Lepadogaster, and the New Zealand Biplocrepis ; the latter being 

 distinguished by the presence of incisor-like teeth in the front of the jaws. 

 The group attains its maximum development in the temperate seas ; all its 

 representatives being marine and littoral. 



The so-called serpent-heads (Channa and Ophiocephalm) are inhabitants of 

 the fresh waters of Africa and the Oriental countries, although more abun- 

 dant in the latter than in the former area. They are long- 

 Section Channi- bodied, fiat-headed fishes, fond of grovelling in the mud, 

 formes.— Family and often leaving their native element to travel some distance 

 Ophiocephalidce. on land, where they progress by the aid of their pectoral fins. 

 In these fish the head and body are covered with scales of 



moderate size, and the fins 

 are without spines, the single 

 dorsal, which is similar to 

 the anal, being low and elon- 

 gated, and the pelvic pair, 

 if present, thoracic in posi- 

 tion, and comprising six soft 

 rays. The most character- 

 istic feature in the structure 

 of the serpent-heads is, 

 however, the presence of a supplemental cavity on each side of the head 

 above the gill-chamber ; and it is probable that this aids in keeping the 

 gills moist while the fish are on land. One yard is no uncommon length 



Fig. 15.— Sekpent-Head. 



