482 PISCES SUB-CLASS I1I.TELEOSTOML 



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 flute-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 stickle-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 

 Section Centris- the soft one like tlie anal is of moderate length. Of more 

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

 Family dominal, arid have no sort of connection with the pectoral 

 CentriscidcB. girdle. These fish constitute the two genera Centriscus 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 Aulostomatidce ; 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 differ from the last in the more normal conformation of their mouths 



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



Section Gobioe- easily recognised by the possession of a sucker on the lower 



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



Family are nearly jugular in position. Both the soft dorsal and 



Gobioesocidce. 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 Diplocrepis ; 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 Ophiocephalus) 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, flat-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- 

 ^ feature in the gtructure 



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 



