No. 566] NEW VARIETIES OF RATS AND GUINEA PIGS 69 



transferring hei 

 mating brother 



From the statements of Messrs. Marriott and Tilling, 

 it is evident that the two variations, which they, respect- 

 ively, have introduced into the rat fancy, are both reces- 

 sive in heredity, as are also the three previously known 

 Mendelizing color variations of rats, viz., (1) the albino 

 variation (with uncolored coat and eyes) ; (2) the black 

 variation (lacking the agouti ticking of the fur) ; and (3) 

 the piebald " hooded" pattern of white and colored fur. 

 Each of these is known to be an independent Mendelizing 

 unit-character. If the new variations are as supposed in- 

 dependent of each other and of those previously known, 

 tliey will make possible the immediate four-fold increase 

 in number of the previously known color varieties of rats. 

 If for the present we adopt a simplified terminology (as I 

 have elsewhere suggested) for the different color varia- 

 tions, employing small letters for such as are recessive 

 in heredity, we may use the following set of symbols : 



White (albino) = w, 



Black = b, 



Hooded = h, 



Pink-eyed = p, 



