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Page:Popular Science Monthly Volume 56.djvu/495

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481
THE BLIND FISHES OF NORTH AMERICA.

small one, and found his tail projecting from the mouth of a larger one."

Wyman found a small-eyed fish in the stomach of an Amblyopsis.

Hoppin was struck by the fact that, if not capable of long fasts, Troglichthys must live on very small organisms that the unaided eye can not discern. Garman found, in the stomachs of Troglichthys collected by Hoppin in Missouri, species of Asellus, Cambarus, Ceuthophilus, and Crangonyx.

All the specimens of Amblyopsis so far taken by me contained very large fatty bodies in their abdominal cavity, a condition suggesting abundance of food. The stomachs always contained the débris of crustaceans, a closer identification of which was not attempted. One young Amblyopsis disappeared on the way home from the caves, and had evidently been swallowed by one of the larger ones. A few old ones, kept in an aquarium from May to July, were seen voiding excrement toward the last of their captivity, and their actions at various times suggested that they were scraping the minute organisms from the side of the aquarium. The young Amblyopsis reared in the aquarium seemed to feed on the minute forms found in the mud at the bottom of its aquarium. Some Cœcidotæa placed in the aquarium of the young soon disappeared, and the capture of one of these was noted under a reading glass. The fish was quietly swimming along the side of its aquarium; when it came within about an inch of the crustacean it became alert, and with the next move of the Cœcidotæea it was captured with a very quick, well-aimed dart on the part of the young fish. Others were captured while crawling along the floor of the aquarium. From all things noted, it seems very probable that Amblyopsis is a bottom feeder, and that it also picks food from the walls of the caves. It is not at all improbable or impossible that food should be captured at the surface or in open water, but there seems no warrant for Cope's supposition that Amblyopsis is a top feeder. I have frequently seen larger specimens, which had been in captivity for several weeks, nosing about the bottom of the aquarium, with their bodies inclined upward in the water and quietly taking in the organic fragments at the bottom. An Asellus stirring about at such a time always produced an unusual alertness.

The number of respiratory movements of Amblyopsis averaged nineteen a minute in five observations, reaching a maximum of thirty in a small individual and a minimum of fourteen in a large one. This is in strong contrast to Chologaster, the number of whose respiratory motions reached an average of eighty per minute in five observations, with a minimum of fifty-six and a maximum