176 LOWER VERTEBRATES. 



Gai", or gar-fish, is a name generally applied by the English-speaking peoples to 

 fishes having both jaws prolonged into elongated, narrowed, but stout bills. These 

 elongated jaws are beset with numerous well-developed and sharp-pointed teeth. The 

 dorsal and anal fins are far back, and opposite, and more or less developed, the 

 dorsals sometimes being quite large and almost sail-like. Such fishes have been distin- 

 guished as a family under the name Bet^onid^, and a number of anatomical characters 

 confirm the separation from the Exoccetidse, with which they have been generally con- 

 founded. It is noteworthy that the bones of all the species examined are greenish. The 

 body is covered with cycloid scales, generally of a veiy small size, and the latei-al line 

 is decurrent, and runs low down on the sides. The species are quite voracious; and 

 those of large size may be even dangerous to man himself. " They are very agile, and 

 may occasionally be seen to leap out of the water. It seems that this propensity may 

 be not without some inconvenience, or even danger, especially in the case of the large, 

 stout-billed species. Mr. S. Archer ' was being pulled off from the shore to H. M. S. 

 Himalaya in the harbor of Aden, when a fish jumped out of the water over the boat, 

 and in doing so struck the hat of another oflicer, and knocked it into the water. When 

 the hat was recovered ' there was found ' in the hard felt a slit about four inches in 

 length.' The fish was doubtless a gar. Professor Moseley, in comments upon this 

 incident, asserts that 'it is the constant habit of large Belones,' — some of which 

 attain a length of five feet, — ' when startled, to move along the surface of the water 

 with astonishing rapidity.' Professor Moseley had 'seen them thus spring out of the 

 water, when scared by a boat,' and had been told ' that in some of the Pacific islands 

 these fish not uncommonly cause the death of the natives, who, when wading in the 

 water, have their naked abdomens speared by the sharp snouts of the fish, with the 

 result of causing peritonitis. The fish appear to bound blindly away from danger, and 

 strike any object in their way haphazard.' " 



The typical genus is Belone, and it is to this that the common gar-pike (£. viilga- 

 ris) belongs ; but the American species are distinguished by the absence of gill-rakei's, 

 while Selone has them well developed, and also by the absence of teeth on the vomer 

 or palatines. The tail, or caudal peduncle, is likewise generally more or less depressed 

 and flattened outwards, ending sideways in callous ridges. In allusion to this last 

 character, the generic name Tylo&nrus has been applied to them. Five species 

 have been obtained along the eastern American coast, and one, T. exilis, on the 

 Pacific side. The common species of the north Atlantic, T. marinus, although a true 

 salt-water fish, often ascends far up into the fresh waters. A notable species, on 

 account of the robustness and sjnke-like form of the jaws, is T. glacUus, of the Florida 

 coast and the neighboring Caribbean and gulf seas. 



Sub-Oedee VII.— PERCESOCES. 



We come now to a group of fishes which, on one hand, is evidently related to the 

 three sub-orders just described, and, on the other, to the great host of Acanthop- 

 terygious or spiny-finned fishes which hereafter follow. The appropriate name, 

 Percesoces, indicating this combination of the characters distinctive of the typical 

 perch-like fishes and the pike-like form, was given by Prof. Cope. The group thus in- 

 termediate may be defined as teleost fishes with the ventrals sub-abdominal or abdom- 

 inal, a spinous dorsal fin developed in addition to the soft, and the air-bladder destitute 

 of connection with the intestinal canal. The group is now represented by but few 



