326 



from the same locality, the ratio of width to length varying from 0.65 

 to 0.73. 



In addition to the increase in size southward, there is a tendency to 

 an increase in the intensity of the colors in the same direction, with a 

 stronger contrast between the light and dark markings. These differ- 

 ences, taken collectively, have given rise to several nominal species, of 

 which the P. hernandezi of Wagler and P. psora of Gray have become 

 the most prominent. The species normally presents a considerable range 

 of color- variation, tending on the one hand more or less to melanism and 

 on the other to albinism. On these extreme phases of coloration have also 

 been based other nominal species, as the P. obscurus of Wiegmaun and 

 the P. nivea of Gray. All these names have been already placed by 

 Gray, in his later notices of the group, under the head of P. lotor, but 

 separated as being varietally distinct. It seems doubtful, however, 

 whether even the large southern form, usually called hernandezi^ is 

 really entitled to subspecin'c recognition. 



Measurements, of thirty-six slculls of PROCYON LOTOR. 



PUTOEIUS VlSOff. 



Eighteen -skulls from the northern parts of the continent, mainly from 

 Alaska, average 2.66 in length and 1.58 in width, the extremes being, 

 length, 3.02 and 2.30; width, 1.90 and 1.40. Thirteen skulls from the 

 highlands of Northeastern New York average 2.40 in length and 

 1.34 in width, the extremes being, length, 2.60 and 2.17. Three skulls 

 from Pennsylvania (undoubtedly males) average 2.49 in length and 1.48 

 in width. In the northern series, the sex of the skull is given by the 

 collector, whence it appears that the twelve males have an average 



