MATERIAL. 75 



a few fertile males appear. The percentage of fertile males gradually 

 increased in later generations. 



The Cavia cutleri stock was derived from animals captured by Pro- 

 fessor Castle in Peru in 191 1 . Like C. rufescens, these are much smaller 

 than the guinea-pig. All show the agouti pattern. The color is 

 described on page 59. Unlike C. rufescens, C. cutleri breeds freely hi 

 captivity and crosses readily with the guinea-pig. The male and 

 female hybrids are fertile. 



The lea stock of guinea-pigs was derived from 3 guinea-pigs which 

 were obtained by Castle near lea, Peru, in 1911. They were as large as 

 or larger than average guinea-pigs, and of a rich golden agouti color, 

 very different from C. cutleri. Two independent color variations 

 appeared at once in the pure stock, viz, black (aa) and red-eye (C r C r ). 

 Such variations are very uncommon among wild species of animals; 

 e. g., none has occurred within the pure rufescens or cutleri stocks. 

 Both of these variations are found in domesticated guinea-pigs in Peru 

 (Arequipa stock). From the description of Cavia tschudii, quoted in 

 Waterhouse (1848) under the name C. cutleri Tschudi, it seems clear 

 that our lea stock is the same as the former, which was likewise 

 described from lea. In view, however, of the size, color, and possession 

 of recessive color varieties found among tame guinea-pigs of Peru, 

 there can be little doubt that they are feral porcellus. 



The Arequipa stock comes from a pair of guinea-pigs brought from 

 Arequipa, Peru, by Castle in 1911. He obtained them from Indians 

 who had them under domestication. Owing to the early death of the 

 only female, no pure stock could be developed, but numerous descen- 

 dants have been derived from the original male 1002, a sepia-cream 

 agouti with white and cream spots, demonstrated to be of constitution 

 EEAaBBPpC d C r , and from a son of the original pair, male 1007, a 

 yellow agouti with white and yellow spots, demonstrated to be of con- 

 stitution EeAaBBPPCjjCd. These were crossed mainly with the 4-toe 

 and BW stocks, which are described below. For a full discussion of the 

 origin and nature of the pure cutkri, lea, and Arequipa stocks, see 

 Parti. 



The Lima stock comes from 8 guinea-pigs obtained from Indians near 

 Lima, Peru, by Professor Brues in 1913. These guinea-pigs and their 

 descendants have only recently been crossed with other stocks. There 

 have been no agoutis in this stock. The pink-eye and yellow variations, 

 as well as white spotting (but not yellow spotting), have occurred in 

 this stock. A pink-eyed red, the lowest recessive, of this stock is of 

 constitution eeaaBBppCC. There were both rough-furred and smooth- 

 furred individuals in the original stock. 



The following stocks come from guinea-pigs obtained from fanciers 

 by Professor Castle and have been maintained for several years at the 

 Bussey Institution. 



