FISHES. 97 



called, the long-nosed gav or the bill-fish, Lejndosteus osseus. This species is widely 

 distributed throughout the United States in lakes and rivers from Lake Champlain to 

 Texas. It reaches a length of about five feet. Its deveIo|)nient has been studied by 

 Alexander Agassiz, Balfour, and Parker, and Dr. E. L. Mark, though the latter has 

 not, at the time of writing, published his results. The fish are nocturnal in their 

 habits, and in the nights of the last of May and the first of June they approach the 

 shallow water in large numbers for the puri)0se of laying their eggs. These eggs are 

 covered with a very sticky envelope of complicated structure, which immediately 

 adheres to any object with which it is brought in contact. In its development it is 

 much like the bony fishes. When it hatches from the egg it has a very large mouth 

 with a row of suckers above. By the aid of these it attaches itself to submerged 

 stones. Now the fins begin to appear, and in the space of two or three weeks the 

 suckers disappeai-, and the young gar-pike swims freely. 



The broad-nosed gar-pike, i. plati/stotnus, is smaller than the preceding, and is 

 rather more southern in its range, while the alligator gar, X. iristtechus, is a much 

 larger form, reaching a length of eight or ten feet. It lives in the rivers of the 

 southern states, and extends south to Central America, and across into some of the 

 West India Islands. This is made the type of a distinct genus, Atractosteus, on account 

 of two rows of teeth in the jaws. 



Order VII. — HALECOMORPHI. 



This order and the last are frequently united as members of a group known as 

 Holostei, which, besides the ossified skeleton, have several other structural features in 

 common. The only living genus is Amia, the type of the family Amiid^. Ainia is 

 even more closely related to the bony fishes than are the gar-pikes. It is covered with 

 large, round scales, lacks the shingle-like fulcra on the fins, and has the vertebras 

 concave at both ends, as in the teleosts. These points, together with other superficial 

 ones of minoi' importance, gi\e the bow-fin a herring-like appearance, and formerly 

 led to the classification among the 



clupeoids. The ordinal name, Hal- ^g--»-gg" '" ""-Z' — ----. 



ecomorphi, also refers to this appear- ^^^^ Zj\ J\ ~~ ---^"^ 's^ 



ance, and means shad-like. Amia ^^^^^^>^i' ^ 



6Tt/«a, the bow-fin, mud-fish, dog-fish, ^^^""^'■'^^''^^N^Sr''^'^"^.; \ ^~ - '^^ 



brindle, sirindle, 'John A. Grindle,' „ „, , ■ , v. a 



'^ ' ' Fig. 71. — .-Imfa cah'rt, bow-fin. 



or lawyer, as it is variously termed, 



is the only known species. In color it is dark olive or blackish above, and faintly 

 marked with dark on the lighter sides. The sexes can readily be sejiarated by a 

 round black spot, ringed with lighter orange or yellow at the base of the caudal fin 

 of the male, which is lacking in the female. A difference is also noticeable in size, 

 the female reaching a length of two feet or more, the male but rarely exceeding 

 eigliteen inches. As in the gar-pikes, the air bladder of the bow-fin is celhdar and 

 functions as a lung. On the mode of res])iration in both genera, Dr. B. G. Wilder has 

 made some interesting observations. Before his experiments it had frequently been 

 noticed that the gar-iiike rises at intervals to the surface of the water, emitting at 

 each time several bubbles of air, but whether air was taken in was not certain, though 

 from the amount exhaled this seemed probable. Dr. Wilder took an adult bow-fin, 

 which was kept in an aquarium, and gradually accustomed it to being handled. 



VOL. HI. —7 



