208 NATURE STUDY REVIEW [7 :8— Nov., 1911 



groups of varieties mentioned. Thus the English animal is 

 short haired and smooth, the Abyssinian is short haired and 

 rough, the angora is long haired and smooth and the Peruvian 

 is long haired and rough. No other distinctive features occur, 

 amateur books on pets to the contrary notwithstanding. 



The large number of distinct varieties into which these four 

 groups are sub-divided rest wholly upon differences in the color 

 of the hair, which again have probably arisen by four or five 

 independent varieties or sports. Color variation in the guinea- 

 pig is more striking and instructive than that in almost any other 

 domesticated animal notwithstanding the large number of color 

 varieties. These, like the groups of varieties based on other char- 

 acters, really depend upon a very few distinctive features, which 

 features are wholly independent of the variations in hair length 

 and coat roughness that form the basis of the four groups already 

 mentioned. 



The principal color varieties are the agouti, of which two 

 sub-varieties differing in depth of color, golden and silver, are 

 recognized ; the black, the chocolate or brown, and the yellow 

 of which several different types may be recognized. The agouti 

 variety is one which has a coat of black or brown hairs tipped 

 with yellow. In the black varieties the yellow tip of the hair 

 is wanting as it is also in the brown variety. Yellows lack black 

 and brown pigment in the fur, though this regularly is seen in 

 the skin of the feet, nose and ears. 



Animals which possess one of the four types of coloration 

 just enumerated, namely the agouti, the black, the brown or the 

 yellow, may show this coloration either over the entire body or 

 in particular regions of the body, the rest being white, or in 

 still other cases known as tri-colors, the animal may show two 

 of the types mentioned as for example black and yellow or brown 

 and yellow, in different regions of its body, while the intermediate 

 regions are wholly uncolored. This is perhaps the most striking 

 and best known color variety of the guinea-pig, the one oftenest 

 seen in bird stores and kept as pets by children. The tri-colored 

 variety known as tortoiseshell, in which large distinct areas of 

 intense black and deep yellow stand out on a white back ground, 

 is a most striking one and is oftenest seen among the English or 

 short haired, smooth varieties. 



In addition to the colored varieties just mentioned, there 

 occur albino or wholly white individuals which have pink eyes, 

 this variation, like the varieties in coat color being wholly inde- 



