The Ganoids 31 
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 tristechus, 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. 
Fic. 23.—Alligator-gar, Lepisosteus tristechus (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 Ama. 
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 zoth, 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 soo 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 
15th 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- 
