9 3 MARINE AND FRESHWATER FISHES 



represented by a simple plate ; air-bladder without a 

 pneumatic duct ; a dermal skeleton composed of numerous 

 indurated polygonal plates, usually developed ; the snout 

 prolonged ; mouth terminal, toothless. 



FAMILY I.— Pipe-Fishes (Syngnathida). 



Gill-openings reduced to a minute opening near the 

 upper posterior angle of the gill-cover ; one soft dorsal fin, 

 no ventrals, and one or more of the other fins frequently 

 absent. 



The Syngnathidtz, including the Pipe-fishes and Sea-Horses 

 {Hippocampi), comprise some of the most remarkable- 



fig. 22. — PIPE-FISH {Nerophis aquoreus). 



looking forms in the world's fish-fauna. The Pipe-fishes, 

 or Sea-adders, as they are sometimes called, are attenuated 

 snake-like fish, represented by as many as five British 

 species. These are the Broad-nosed Pipe-fish {Syphonostoma 

 typhle), No. 184 ; the Greater Pipe-fish (Syngnathus acus), No. 

 185; the Ocean Pipe-fish {Nerophis aquoreus), No. 186; 

 the Snake Pipe-fish (N. ophidion), No. 187; and the Worm 

 Pipe-fish (N. lumbriciformis) , No. 188. The majority of 

 these types will be found among the spirit-preserved series of 

 fish forming the Day Collection. A peculiarity common to 

 all the Pipe-fishes, and also the Sea-Horses, is connected 

 with their mode of locomotion. This is effected entirely 

 by the action of the unpaired dorsal fin, the rays of which, 



