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THE AMERICAN NATURALIST [Vol. XLVIII 



By various combinations of these variations, if each is 

 independent of all the others, 32 varieties become possi- 

 ble. Half of these varieties will be albinos, white and so 

 visibly indistinguishable. The other 16, we have reason 

 to suppose, will look different from each other. Pre- 

 viously we had but four of these, the first four in the fol- 

 lowing list of the theoretically possible 16. 



1. Normal or wild agouti. 



2. b black, 



3. h hooded, 



i. bh black hooded, 



6. pb pink-eyed black, 



7. ph pink-eyed hooded, 



9. y yellowf 



10. yb yellow black (i. c, non agouti yellow), 



13. ybh yellowback hooded. 



14. ypb yellow pink-eyed black, 



15. yph yellow pink-eyed hooded, 



16. ypbh yellow pink-eyed black hooded. 



Varieties 1-4 have been known for some time; they 

 have constituted the fancier's entire repertoire up to the 

 present time. Varieties 5 and 9 have apparently arisen 

 as wild sports obtained by Marriott and Tilling, respect - 

 ively. By crosses these gentlemen have apparently ob- 

 tained varieties 6, 7, 8, and probably 10. Varieties 11-16 

 are as yet unknown, but will doubtless soon be produced. 

 Corresponding with each of the 16 colored varieties, an 

 uncolored one should be possible of production, which 

 would transmit in crosses with any colored variety the 

 characteristics indicated by its formula. Albinos cor- 

 responding to colored varieties 1-4 are positively known 

 to occur; their symbols would be if, trb, >rh and irhh, re- 

 spectively. Symbols for the remaining VJ expected varie- 

 ties may be formed in like fashion, by prefixing ir to the 

 combinations already given. 



All the five unit-character variations, which in different 

 combinations are responsible for the color varieties of 



