PIPE-FISHES. 683 



brane on the lower side of tlie tail, without a pouch being 

 developed. 



Three species from the coasts of Australia, The protective 

 resemblances with which many Lophobranchs are furnished, 

 attain to the highest degree of development in the fishes of 

 this genus. Not only their colour closely assimilates that 

 of the particular kind of seaweed which they frequent, but 

 the appendages of their spines seem to be merely part of the 

 fiicus to which they are attached. They attain a length of 

 12 inches. 



Hippocampus. — Trunk compressed, more or less elevated. 

 Shields with more or less j^rominent tubercles or spines. Occiput 

 compressed into a crest, terminating at its supero-posterior corner 

 in a prominent knob (coronet). Pectoral fins. The males carry 

 the eggs in a sac at the base of the tail, opening near the vent. 



A singular resemblance of the head and fore part of the 

 body to that of a horse, has given to these fishes the name of 

 " Sea-horses." They are abundant between and near the 

 tropics, becoming scarcer in higher latitudes. Some twenty 

 species are known, some of which have a wide geographical 

 range, as they are often carried to great distances with floating 

 objects to which they happen to be attached. — Acentronura 

 is a genus closely allied to HipiJocampus. 



SIXTH OEDER— PLECTOGNATHI. 



Tcleosteous fislies with rough scales, or with ossifications of 

 the cutis in the form of scutes or sjnnes ; shin sometimes entirely 

 naked. Skeleton incompletely ossified, with the vertebrae in 

 small numher. Gills pectinate ; a narrow gill-opening in front 

 of the pectoral fins. Mouth narrow ; the hones of the iipper 

 jaw generally firmly united. A soft dorsal fin, belonging to the 

 caudal portion of the vertebral column, opposite to the anal ; 

 somctiines elements of a spinous dorsal besides. Ventral fin 

 none, or reduced to spi^ies. Air-bladder without pneumatic duct. 



