PISCES 151 



to be little more than a head with an enormous gaping mouth 

 (Fig. 74, E and F). The anterior spine of the dorsal fin is modi- 

 fied so as to form a sort of "fishing-rod" which hangs over the 

 mouth and has pendant from its tip a fleshy pad or bait. The 

 Anglers are almost scaleless and are bottom-feeders, both of which 

 characters are taken to be evidences of senescence. Some of them are 

 abysmal forms that have been called "Bathymal Sea Devils"; these 

 are even more degraded in structure than are the more typical An- 

 glers. One of the strangest of all fishes is the Sargassum Fish, a form 

 that lives a drifting life among the masses of Sargassum weed; its 

 camouflage of color pattern and raggedly weed-like fins make it merely 

 a part of the general floating mass. The Bat-Fish represents perhaps 

 the climax of senescent degeneration in this group; it is a very broad, 

 flat bottom-feeder, with wing-like pectoral fins. 



Fool-Fishes, Trunk-Fishes, Porcupine-Fishes, Puffers, and 

 Head-Fishes (Plectognathi) . This final sub-order of teleosts is 



FIG. 92. Hawaiian Trigger-Fish, Ballistapus rectangulus. (Redrawn after 

 Jordan and Evermann.) 



perhaps the most highly specialized of all, and is believed to be 

 derived from the family Acanthiuridae of the Acanthopterygii, which 

 are characteristically short, high, compressed fishes, typified by 

 Zanclus (Fig. 86). The Plectognathi comprises a collection of the 

 strangest creatures that the sea affords. Of these the Trigger- 

 Fishes are the most moderate in structure, not unlike some of 

 the Acanthopterygii in their high, compressed proportions; a modi- 



