246 ' THE AMERICAN NATURALIST [Vol. XL VI 



from 62.5 to 90 black, ranges distinct from and not at all over- 

 lapping those for Series A reared in darkness. 



Series C (16 individuals), living in the outdoor pool under 

 natural conditions, had an average body color of 86.6 black and 

 13.4 per cent, non-black (4.5 white, 3.1 orange and 5.8 yellow), 

 the extremes ranging from 77.5 to 93 per cent, black. The 

 head color averaged 78.3 black and 21.7 non-black (7.7 white, 

 4.2 orange and 9.8 yellow) with 61 per cent, and 90 per cent, 

 the extremes in amount of black. The data for all three series 

 are shown together in the adjoining table. 





Body 

















S 



•J | 



ij 



Series A (cave) : 



















Extremes: 



70.5 









29. o 



51.0 









Lightest 













27.0 









Averages 













38.0 



26.7 







Series B (laboratory) : 





















Extremes: 



Darkest 













90.0 







10.0 













18.0 









37.5 





Mi.l 







6.8 



13.9 







4.0 11.5 



23.9 



Series C (pool) : 

 Extremes: 













1)0.0 







10.0 



Lightest 











■22..) 









39.0 







4.5 



3.1 



5.8 





7S.3 







It will be noted that the series reared in laboratory light 

 (Series B) and the one developing under natural conditions in 

 the outdoor pool (Scries f ) agree very closely in the amount of 

 pigment development, the average percentages of black in the 

 body color determinations being 86.1 and 86.6, and for the head 

 color 76.1 and 78.3 respectively, while the extremes for the two 

 series differ but slightly. However, the most significant fact 

 is that these series differ so sharply from Series A reared in the 

 dark and having an average body color of only 49.7 per cent, 

 black and an average head color of 38 black. On the average 

 those reared in darkness have about four times as much non- 

 black in the body color as those reared in light, while the darkest 

 individual of the cave scries, really aberrant for that series 

 because it is so dark with 70.5 per cent, black in the body color 



