The Ganoids 3 1 



ally common throughout the Mississippi Valley. It has a short 

 broad snout like the alligator gar, but seldom exceeds three feet 

 in length. In size, color, and habits it agrees closely with the 

 common gar, differing only in the form of the snout. The form 

 is subject to much variation, and it is possible that two or more 

 species have been confounded. 



. The great alligator-gar, Lepisosteus tristcechus, reaches a 

 length of twenty feet or more, and is a notable inhabitant of 

 the streams about the Gulf of Mexico. Its snout is broad and 

 relatively wide, and its teeth are very strong. It is very de- 

 structive to all sorts of food-fishes. Its flesh is worthless, and 

 its enameled scales resist a spear or sometimes even shot. 



FIG. 23. Alligator-gar, Lepisosteus tristcechus (Bloch). Cuba. 



It breathes air to a certain extent by its lungs, but soon dies 

 in foul water, not having the tenacity of life seen in Amia. 



Embryology of the Garpike. Mr. Alexander Agassiz has 

 given an account of the embryology of the garpike, of which the 

 following is an abstract: 



"The garpike comes up the St. Lawrence in May, lays its 

 eggs about the 2oth, and then disappears. The eggs are large, 

 viscous, stick fast in an isolated way to whatever they fall 

 upon, and look much like those of toads, having a large outer 

 membrane and a small, yolk. Artificial fecundation failed, 

 but about 500 naturally-laid eggs were secured, of which all 

 but 30 perished through mold. The young began to hatch 

 in six days. Out of 30 young hatched, 27 lived until the 

 1 5th of July. Connection with the sharks appears in the 

 similarity of the branchial arches and by the presence of the 

 lateral fold in which the pectoral fins are formed; the way 

 the tail is developed is very like that of the bony fishes. 

 Among the Ganoids it appears, as well as in ordinary fishes, 

 the dorsal cord is straight at first, then assumes a slightly up- 



