From the time of Richardson's account, it was not until 1848 
that specimens were reported again. The naturalist T. R. Peale 
of the Wilkes Exploring Expedition collected two mountain beaver 
specimens in the neighborhood of Puget Sound, which he described. 
He also discussed their habits and abundance in that area, 
Soon after, in 1854, Audubon and Bachman quoted Lewis and Clark's 
account as first published, They also summarized Richardson's work, 
made inferences drawn from the anatomy as to the animal's habits, and 
added some statements concerning its distribution. 
Under the supervision of Spencer F. Baird (1857), the naturalists 
J. S. Newberry, J. E. Cooper, G. Suckley, and G. Gibbs of the Pacific 
Railroad Explorations gathered material and made valuable observations 
on the distribution and habits of the mountain beaver. Baird suggested 
that Rafinesque's specific name rufa be accepted as the proper specific 
mame of the species, and Coues (1877) adopted it as such. 
From salient internal characters similar to those of the beaver 
(Castor canadensis), Baird (1858) placed the animal in the subfamily 
Castorinae of Sciuridae. 
In 1864, Peters of the Berlin Museum described a California 
mountain beaver as a new race, to which he applied the name Haplodon 
leporinus var. californicus, said to have come "aus den Gebirgen 
Californiens," 
On the basis of original anatomical studies and a review of the 
literature, Coues (1877), in his comprehensive monograph, adopted the 
genus Haplodon for the mountain beaver. 
In 1886, Merriam described a species of mountain beaver (Aplodontia 
major), from California and in 1899 described four more races: A. 
pacifica, A. phaea, A. olympica, and A. major rainieri. 
In 1914, Kellogg and Taylor described two additional mountain 
beavers from California: A. chryseola Kellogg, and A. nigra Taylor. 
Two years later, Taylor described three more races: A. californica 
columbia, A. rufa grisea, and A. humboldtiana. 
Monographic studies of the life history of the mountain beaver 
include those of H. E. Anthony (1916), Charles L, Camp (1918), 
Theo. H, Scheffer (1929), and Walter P, Taylor (1918). Taylor summa- 
rized the full taxonomic history of the genus. 
