AET. 20. STUDIES OF THE BITING LICE — EWING. 39 



do get, the writer believes, an infestation witli the same group of 

 ectoparasites. 



The convergence of the pelage environment of the two diverse mam- 

 malian groups is a necessity to the crossing over of many ectopara- 

 sites from the one to the other. That such a crossing over does occur 

 in nature, we have an abundance of evidence, and particularly in the 

 case of the mallophagan family Gyropidae do we have the data 

 indicating in most convincing terms that they have jumped the 

 phylogenetic gap between the order Rodentia and the orders Pri- 

 mates and Ungulata, going from their original and most favored 

 rodent hosts to the less favored primate and ungulate hosts. 



HOST LIST. 



EDENTATA. 



Beadypodidae. 



Bradypus tridactylus (sloth). 



Oyropus hispidus Nitzsch.' (South America.) 



RODENTIA. 



Caviidae. 

 Cavia anolaimae. 



Gliricola distincta Ewing. (Colombia.) 

 Cavia cobaya (guinea-pig). 



Gyropus ovalis Nitzsch. (Everywhere the host is kept in domestica- 

 tion.) 



OUricola porceUi (Linnaeus). (Everywhere the host is kept in domes- 

 tication. ) 

 Cavia cutleri. 



Gliricola j)orcelli (Linnaeus). (Peru.) 

 Cavia rufescens. 



Gliricola porcclli (Linnaeus). (Straggler?) 

 Cavia tschudii. 



Gyropus ovalis Nitzsch. (Peru.) 



ParaffUricola qiindrisetosa Ewing. (Peru.) 



Gliricola porcelli (Linnaeus). (Peru.) 

 Cavia, species. 



Protogyropus nonnalis Ewing. (Argentina.) 

 Cavia, species. 



Paragliricola quadrisetosa Ewing. (Argentina.) 

 Kerodon australis. 



Tetragyropus lineatus (Neumann). (Brazil.) 

 Kerodon moco. 



Tetragyropus lineatus (Neumann). (Brazil.) 



Gliricola porcelli perfollatus (Neumann). (Brazil.) 

 Kerodon spixii. 



Heterogyropus hcteronyclius Ewing. (Brazil.) 



Paragliricola quadrisetosa Ewing. (Brazil.) 



1 This species belongs to the subfamily Gyropinae, but its iuclusion in the genus 

 Gyropus is only tentative. The record is to be questioned. (See discussion under 

 Geographical and Host Distribution.) 



