436 University of California Publications in Zoology — (Vou. 17 
bers of the order have been presumed to be derived, and constitutes 
a stock which is one of the most conservative known in the class 
Mammalia. The family to which it belongs (the Aplodontiidae) was 
the sole mammalian family cited by Wallace (1876, p. 127), as char- 
acteristic of his Californian subregion of Nearctica, and is remark- 
able for its present restricted distribution, being found only on the 
Pacific coast of North America, in an area which may be bounded 
roughly by southern British Columbia on the north, the Sierra- 
Cascade mountain system on the east, and the latitude of San Fran- 
cisco Bay on the south (see map, text-fig. H). 
The unusual characters of the genus Aplodontia (see pls. 26, 27), 
together with the scarcity of fossil remains representative of it, have 
made the determination of its systematic status a matter of exceptional 
difficulty. Minding (1829, p. 86) referred the genus Anisonix 
[= Anisonyx = Aplodontia (part)| to the family Prensiculantia, 
in which it is associated with twenty-seven other genera, ranging from 
Castor, Hydromys and Mus to Bathyergus, Tamias and Chiromys. 
Two years later Bonaparte (1831, p. 20) associated the genus Aplo- 
““section’’ Sciurina of the 
family Muridae. Swainson (1835, p. 388) put Aplodontia in his 
“Division I’’ of the Order Glres which contained twenty-two addi- 
tional genera. By Schinz (1845, pp. 120, 139) the genus was referred 
dontia with twenty other genera in his 
to the family Cunicularia, in which were included also arvicolines, 
octodonts, pocket gophers, and mole-rats. Gervais (1854, p. 364) 
grouped Aplodontia with the pocket gophers. Baird (1857, p. 350) 
included Aplodontia in the subfamily Castorinae; Lilljeborg (1866, 
opp. p. 9) referred it to the porcupines; Peters (1865, pp. 177, 179), 
Alston (1876, p. 66, and pl. 4, opp. p. 61), Coues (1877), pp. 543, 
601) and others placed it with the squirrels. Guill (1872, p. 22) refer- 
red the Haploodontidae to a superfamily Haploodontoidea, listing it 
as equivalent in rank to the Castoroidea and Sciuroidea ; Zittell (1894, 
p. 528) included the Haplodontidae with certain aberrant families of 
rodents in his Protrogomorpha; and Thomas (1896, pp. 1014, 1015) 
accorded to the Aplodontiidae and Anomaluridae separate group 
rank, leaving it for further research to show their true relationships. 
The latest classification is that of Matthew and Osborn in 1910, 
according to which the Aplodontiidae are associated with three extinct 
families of rodents in the superfamily Aplodontoidea. 
Thirteen forms of Aplodontia Recent have been deseribed, nine 
being here recognized. The first formal description was that of 
