76 KANSAS ACADEMY OF SCIENCE. 
They may also have been swallowed to act by their weight as ballast to coun- 
teract the natural buoyancy of the body, like the stones of considerable size 
usually found in the stomachs of alligators, and which are supposed to have been 
swallowed to assist them in remaining at the bottom. 
The fact that there were no grains of black sand among it, which does not 
polarize, would rather seem to lend support to the digestive theory; inasmuch as 
white sand, being composed of quartz, or almost pure silica, and hard enough to 
scratch glass, would naturally be selected by them to assist in the grinding or 
trituration of their food, rather than the much softer black sand. 
There was observed at one place an agglomeration of small, round grains, 
quite smooth outside, like very small fish eggs, which they perhaps were, or spores 
of some small toadstool or other fungus. They were transparent, and not much 
over one-quarter the size of the grains of sand mentioned above. 
A great quantity of some dark-colored substance, finely comminuted and ap- 
parently of animal origin, was found, perhaps the remains of worms or meat of 
some kind; but, although most carefully sought for, there were no feet, wings, 
scales of lepidoptera, parts of insects, crustaceans, or muscular fibers of any sort 
among it, such as would have been likely to have survived the digestive process 
and given a clew to its character. 
As we may see from the smallness and degree of convexity of their eyes that. 
fish must be capable of seeing things infinitely smaller than would be visible to 
the human eye, this matter was perhaps composed of minute particles of both 
animal and vegetable origin which the fish met with and swallowed as it swam 
about, and which were perhaps too small to preserve any definite recognizable 
character, especially after passing through the stomach. 
Their principal food, though, to judge from the great numbers of frustules of 
different kinds found in the stomach and intestines, were diatoms, the outer 
shells of which, being composed of almost pure silica, are well-nigh indestructible 
by the digestive process, fire, or the strongest acids. 
After preparing the diatoms for examination under the microscope, it was 
seen that the greater part of these small organisms in view were Navicule of 
small size, of the type known as radvosa, arenaria, etc., of two or three sizes, or 
of the /anceolata form, with divergent strizw, such as are figured in Schmidt’s 
Atlas of the Diatomaceae (plate 47) or varieties of that type. (See fig. 26, pl. 
III.) Some were much larger and some smaller than the figure, but mostly of 
the same general type. 
Gomphonema was, as usual in Kansas gatherings, very rare, though four 
or five species were met with. Cymbella, also one of the commonest forms any- 
where East, was equally scarce; and I had about concluded that none except 
small forms were present, when I unexpectedly came across an Amphiprora of 
the largest size (fig. 9, pl. IL), and of a decidedly rare variety, not found in the 
forty-four Cincinnati slides. The individuals of this family are among the largest 
diatoms; and they were remarkably abundant, as if there was a savor or a large 
body of nourishment in them which had especially appealed to the fish’s taste. 
Figure 10, plate II, is another individual in a different position. 
A noticeable thing was not only the abundance of this large and rare 
Amphiprora not found at Gage’s pond or Silver Lake, but the remarkably 
large number of fine Pleurosigme, mostly spencerii or varieties, every field 
containing at least one and often several. The figure I giveof it (No. 18, pl. III) 
would have been better if drawn on a larger scale; but I did not have room on 
the plate for one larger. 
An unusually large form of Amphora lineata, not found at Gage’s pond, 
