115 



forward under the head, movhip- friadually to the front with increas- 

 ing size. This lish is not over three inches in length. It occurs 

 in rivers and smaller strenms, as well us in lakes and ponds through- 

 out the State. We have collected it from the Illinois Eiyer and 

 various tiilmtaries, as well .is from the lakes couiiectc-d wiUi that 

 stream, and from ponds and creeks throughout Southein Illinois, 

 It has also heen taken in the Calumet Eiver near Ciiicago, and 

 from lakes in that vicinity, hut is not known to occur in Lake 

 Michigan. It is said to be nocturnal in its hahits, by Dr. C. C. 

 Abbott, who kept specimens in an aquarium for Forae time.* The 

 same author reports ihat in confinement it feei-ls voraciously upon 

 small fishes, especially immature <"yprinidpe; and for this reason 

 he bestowed upon it the name of jiirate pcrcli,, by which it has be- 

 come generally known among ichthyologists. The observations 

 presently to be detailed will show, however, that his specimens w^ere 

 doubtless forced to feed so largely upon fishes for want of food more 

 natural to them, since in their native haunts fishes make but a 

 small percentage of their ordinary food. 



The intestine of this species is short and simple, less than the 

 length of the head and body without the tail, and distinguished 

 only by the character previously mf-ntioned. The gill apparatus is 

 ineffective, the rakers being very short, thick, blunt, and few, and 

 covered with short spinules. The pharyngeal jnws consist of small 

 plates, covered with short, sharp spmulose teeth, similar to those of 

 the sun-hshes. The mouth is large, but not remarkably protractile. 



The specimens dissected number nineteen, representing seven dif- 

 ferent dates and localities, throughout Central and iSoutbem Illi- 

 nois Some were taken from small temporary ponds left by the 

 retreatmg overflow of streams, others from permanent lakes, and 

 still others from creeks anil rivers. The food from the different 

 locrtlifies varies but little, on the whole, and it is scarcely worth 

 while to discuss the separate collections. That of the^e nineteen 

 specimens was almost purely animal, traces of a minute flowering 

 •plant (Wolffia), and small quantities of fllamentous Algae only being 

 taken by two of the specimens. Fishes were eaten by but two, and 

 were reckoned at two per cent, of the food of the whole. One of 

 these found was recognizable as a cyprinoid, but the other could 

 not be determined. Insects amounted to more than ninety per cent., 

 all of them aquatic, with the exception of a few gnats (Culicidte) 

 taken by eight of the fishes. Nearly half of the food consisted of 

 larvae of Chironomus and Corethra, Aquatic coleopterous larvae 

 were reckoned at eleven per cent., and specimens of Corixa, taken 

 by three of the fishes, at two. A singlt; fish had also eaten Galgu- 

 lus. A fourth of the food consisted of neuropterous larvae (Ephe- 

 meridae and Libellulidae). Crustaceans, though captured by more 

 than half the fishes, made but four per cent, of the food. As far 

 as recognized, this element consisted chiefly of the amphipod, Al- 

 lorc}iest('.s dciitaia, and the common isopod, Asellus. A few speci- 

 mens of Cyprididie were noticed in two of the fishes, and Cyclops 

 and other Copepoda were taken by five. One fish had eaten a 

 Lumbriculus, a species closely allied to the common earthworm. 



*Vt(w. Pliil. Arad. Nat. Sci., IWil, p. 05. 



