256 



The Journal of Heredity 



fication of the two species. The color 

 pattern may vary with the age. and with 

 the particular body of water in which 

 the lish lives. In Cayuga Lake, how- 

 ever, the color pattern of adults seems 

 to be well defined and sufficiently con- 

 stant to permit of identification by this 

 character alone. 



SCAL.\TIOX OF CHEEKS AND OI'EKCULA 



■ The head of a typical pike is illus- 

 trated in Fig. 4. It will be noticed that 

 the scales extend all the way down on 

 the cheeks and but half way down on 

 the opcrcula. On the typical pickerel, 

 Fig. 4,b, both the cheeks and opercula 

 are entirely covered with scales. The 

 three artificially produced hybrids, rep- 

 resented by Fig. 4, c, and the supposed 

 natural hybrid, Fig. 4, d. are nearly 

 identical in so far as the scalation of the 

 head is concerned. About one-third of 

 the lower half of the operculum is 

 scaled while the other two-thirds is bare 

 or has only one or two isolated scales. 

 The hybrids are thus intermediate be- 

 tween the pike and pickerel with re- 

 spect to this character. 



COLOR PATTERN 



The color patterns of the adult pike, 

 Fig. 5, and of a supposed natural hy- 

 brid of mature size (45 cm. long) arc 

 blotches distributed over a darker 

 ground color. In the case of the adult 

 pickerel, Fig. 5, b, the pattern consists 

 of an irregular network of dark lines 

 inclosing a light ground color. 



The artificially produced hybrids 

 have not yet reached the age when the 

 adult color pattern appears, but it is 

 possible to compare the juvenile ])at- 

 tern of the pike, pickerel, and hybrid, 

 F'igs. 5, c, d. e. The jiike and the 

 hybrid resemble each other very closely, 

 the diagonal light bars with broad and 

 darker areas between them being very 

 distinct in both forms. In the case of 

 the juvenile pickerel, the distribution 

 of color is quite different. Instead of 



distinct oblique bars of light color we 

 have rather indistinct bars and scrolls 

 running in various directions. In the 

 region below the lateral line, there is 

 a tendency to form narrow, dark bars 

 with a broader and lighter area be- 

 tween. How constant this pattern is in 

 the case of the pickerel, is not known, 

 but it is not believed to be variable 

 enough to interfere with the recogni- 

 tion of young pickerel in the presence 

 of young pike. Since the adult pike 

 and the supposed natural hybrid closely 

 resemble each other in color pattern, 

 and since a similar condition obtains 

 l.ietween the juvenile pike and the arti- 

 ficially produced hybrid, there is some 

 probability that the mature artificial hy- 

 l)rid will also reseml)le closely in color 

 pattern the natural hybrid. 



SUMMARY OF FIXDINGS 



Let us summarize the facts in the 

 case as follows : 



The overlapping spawning time and 

 the spawning behavior of the pike 

 (Hso.v I ltd IIS) and the pickerel (Hsox 

 rcticulatiis) are such as to permit of 

 the possibility of a natural cross. 



The eggs of the pickerel may be arti- 

 ficially impregnated with the milt of 

 the pike and may develop into healthy 

 hybrids. 



Artificially produced hybrids and 

 supposed natural hybrids are identical 

 in the scalation of the opercula, show- 

 ing a condition intermediate between 

 typical pickerel and pike. 



Typical adult pike and supposed natu- 

 ral liyl)rids are identical in color 

 pattern. 



Juvenile pike and the artificial hy- 

 brids are identical in color patterns. 



Thus there is a probability that ma- 

 ture artificial hybrids will resemble in 

 color pattern the supposed natural 

 hybrids. 



These facts seem to favor the as- 

 sumption that pike and pickerel occa- 

 sion.nllv cross in nature. 



