(82) 
and other dragon flies, May flies, caddis flies), water bugs, 1 (Corixa and 
Notonecta), vegetable matter 4, (algae, Naiadaceae, roots stems and leaves 
of various plants). 
51. Black Cat Fish. Amiurus melas, Raf. (2). Taken in small 
prairie creeks, McLean Co. Stomach of one was full of purely vegetable 
food, consisting chiefly of a mass of confervoid algae ; that of the other con- 
tained no vegetation, but exhibited fragments of various insects, some of 
them terrestrial, and remains of young craw-fishes and aquatic larvae. 
DOG FISHES. AMIIDAE. 
52. Dog Fish. Grinnel. Amia calva, L. (1.) A single small spec- 
imen, 5 in. long, from S. 111., had eaten some Ephemera larvae, a few ostra- 
coda (Cypris) and some confervoid algae, with numerous diatoms. 
GAR PIKES. LEPIDOS TEIDAE. 
53. Broad-nosed Gar. Lepidosteus platystomus, Raf. Seven or 
eight specimens were opened, but the stomachs of all but one were entirely 
empty. This one contained a common river craw-fish, (Cambarus immunis, 
Hagen.) Is the gar a nocturnal feeder? 
SPOON-BILLED CATS. POLYODONT1DAE. 
54. Shovel Fish. Bill Fish. Polyodon folium, Lac. (5.) This is 
by far the most remarkable fish in our rivers, and is not less remarkable in 
its food than its structure. By the fishermen it is supposed to live on the 
slime and mud of the river bottom. The alimentary canal of each of the 
five specimens examined was found full of a brownish, half fluid mass, 
which, when placed under the microscope, was seen to be made up chiefly 
(in one case almost wholly) of countless myriads of entomostraca, of nearly 
every form known to occur in our waters, including many that have been 
seen as yet nowhere but in the stomachs of these fishes. Mixed with these, 
in varying proportion, were several undetermined and probably undescribed 
species of water worms (Annulata), most of them belonging to the family 
Naididae. Sometimes as much as a fourth of the mass was composed of 
vegetable matter, — largely algae, but including fragments of all the aquatic 
plants known by me to occur in the waters of the Illinois, except Cerato- 
phyllum. Occasional leeches (Clepsine"), water beetles (Coptotomus inter- 
rogatus &c.), a few larvae of diptera and Ephemerae and water bugs (Corixa) 
were noticed. Among the Crustacea several specimens of the remarkable 
Leptodora hyalina already referred to were found. 
I have not had time for anything more than a general examination of 
the mass of matter presented, — sometimes more than a pint from a single fish, 
— and cannot, therefore, give a list of the species. Curiously, very little 
mud was mixed with the food. 
