270 Palmer Generic and Family Names of Rodents. 



Palaiotrogus Jager, 1839 Palaiotrogus steinheimensis. 



Paradoxomys l Ameghino, 1885. . Paradoxomys cancrivorus. 



Protechynus Filhol, 1891 Nomen nudum. 



Protoptychus* Scott, 1895 Protoptychus hatcheri. 



l Paradoxomyina Ameghino, Bol. Acad. Nac.Cien., Cordoba, IX, p. 79, 1886. 



Paradoxomydte Ameghino, Mam. Fos. Eepub. Argentina, in Actas Acad. 

 Nac. Ciencias, Cordoba, VI, p. 122, 1889. 



2 "The genus is probably to be regarded as the ancestral type of the 

 Dipodidae, and indicates an American origin for this family." Scott, 

 Proc. Acad. Nat. Sci. Phila., 1895, p. 286. 



