Jordan and Evermann. Fishes of North America. 1017 



the Etheostominw especially being among the most brilliantly colored fishes 

 known; the sexual differences are often great, the females being as a rule 

 dull in color and more speckled or barred than the males. Most of them pre- 

 fer clear running water, where they lie on the bottom concealed under 

 stones, darting, when frightened or hungry, with great velocity, for a 

 short distance, by a powerful movement of the fan-shaped pectorals, then 

 stopping as suddenly. They rarely use the caudal fin in swimming, and 

 they are seldom seen moving or floating freely in the water like most 

 fishes. When at rest they support themselves on their expanded ventrals 

 and anal fin. All of them can turn the head from side to side, and they 

 frequently lie with the head in a curved position or partly on one side of 

 the body. The species of Ammocrypta, and perhaps some of the others, 

 prefer a sandy bottom, where, by a sudden plunge, the fish buries itself 

 in the sand and remains quiescent for hours at a time, with only its eyes 

 and snout visible. The others lurk in stony places, under rocks and 

 weeds. Although more than usually tenacious of vitality, the darters, 

 from their bottom life, are the first to be disturbed by impurities in the 

 water. All the darters are carnivorous, feeding chiefly on the larvae of 

 Diptera, and in their way voracious. All are of small size ; the largest 

 (Percina rex) reaches a length of 10 inches, while the smallest (Microperca 

 punctulata) is, next to Elassoma zonatum, the smallest spiny-rayed 

 fish known, barely attaining the length of an inch and a half. 

 In Europe no E tlieostomince are found, their place being filled by the 

 genus Zingel (Aspro), which bears a strong resemblance to the American 

 forms, a resemblance which may be a clue as to the origin of the latter. 

 The other European genera are Perca, Lueioperca, a near ally of Stizostedion, 

 Gymnocephalus (Acerina), and Percarina. The separation of the Etheosto- 

 mirice into genera is a matter of much difficulty as the structural differ- 

 ences are small, the individual variations great, and the gradations very 

 perfect. We have, hitherto, been disposed to unite them all in one genus, 

 but to do so tends to obscure the relations of the species. Dr. Boulenger * 



man goes a fishing not for " pot luck," but to let escape " the Indian within him." The Johnny 

 has all that ardent desire for perfect freedom that is supposed to be native to this continent. 

 Unless all appearance of captivity be concealed in a well-kept aquarium he will quickly lie on the 

 bottom, dead. Here, at the beginning (for much as we may regret the fact, the death of some 

 individual must precede our acquaintance with the group, and even to some extent with the 

 individual himself), we observe two noteworthy facts, the fish in dying does not turn over, and 

 does not rise to the surface. On dissection, we find that the air bladder is only rudimentary, 

 being structurally but not functionally present, a distinction not without meaning in these days 

 of evolutionary hypotheses. If our tank be so arranged that the conditions are nearly natural, 

 there being an abundance o f stones and weeds on the bottom, our Johnnies will cheerfully live 

 with us and we sna11 be ready to study their individual peculiarities. For it must be known 

 that while all fish are fish, they are so only as all men are men. The children of one family are 

 not more unlike one another than the fishes of one brood might be if the sickly ones and the lazy 

 ones were as carefully guarded as are ours. As it is, they have their individuality. One is con- 

 stantly darting over and among the stones, never resting, moving his head from side to side when 

 his body is for a moment still. Another will lie for hours motionless under a stone, moving only 

 for a few inches when pushed out with a stick. These peculiarities of temperament are import- 

 ant factors in the problem of life, and from such differences under varying conditions, may have 

 resulted forms which wo now designate as different species. "The Johnny Darters," Jordan & Cope- 

 land, Amer. Nat., 1876. 



* Dr. Boulenger gives the following synopsis of the genera of Percidx : 

 I. Head with the nuciferous cavities moderately or feebly developed above and on the sides; 



dorsal fins distinct. 

 A. Body more or less compressed. 



