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THE AMERICAN NATURALIST [Vol. XLVIII 



record, crediting the characteristic Trichodectes pilosus 

 of the horse to a coypou of South America (in the menag- 

 erie of the Jardin des Plantes in Paris), is certainly 

 either a false record or one of rather extraordinary 

 straggling. The two Mallophagan species from these 

 South American tuco-tucos belong to the genus Gyropus, 

 which is the Mallophagan genus especially characteristic 

 of the related South American families, the Caviidas 

 (guinea-pigs), the Dasyproctidae (agoutis), and the Chin- 

 chillidae (chinchillas and vizeachas) (see following 

 paragraphs). 



The guinea-pigs and mocos (family Caviidae) are repre- 

 sented by three species, and are strongly parasitized by 

 Mallophaga. They have no Anoplura. The domesticated 

 form, which is variously held to be a species distinct 

 from any wild one now known, or a variety of the wild 

 species, Cavia cutleri, harbors two well-known species of 

 Gyropus, namely G. ovalis and G. gracilis (this latter is 

 held by some students to be of distinct genus). In addi- 

 tion, Piaget has described a species of Menopon (bird- 

 infesting genus) from it, and Paine and I have described 

 another Menopon from it from collections we have had 

 from Peru and Panama. We have also found this latter 

 species on the wild guinea-pig, Cavia cutleri, from Peru, 

 and from this host Paine has described a species of 

 Gyropus peculiar to this host. From the Brazilian moco, 

 Kerodon moco, has been recorded a variety of Gyropus 

 gracilis, one of the familiar species of the domestic 

 guinea pig, as well as another species of Gyropus peculiar 

 to the moco. Recently Cummings has described a new 

 Mallophagan taken at Villa Rica, Paraguay, from the 

 wild guinea-pig, Cavia aperea. For this new species he 

 established a new genus called Trimenopon. Asa matter 

 of fact the species is so much like Kellogg and Paine 's 

 Menopon jenningsi, except for its markedly larger size, 

 that I am not at all sure it should be added as a fourth 

 guinea-pig parasite. 



A single agouti, Dasyprocta aguti, from Brazil, repre- 

 sents the family Dasyproctidae. From it have been de- 

 scribed two species of Gyropus peculiar to it. 



