556 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
consideration of external form, upon which a genus Haplodon may be 
properly based. In the account of the species which is to follow, much of 
the structure of the animal is given in detail, without reference to the sys- 
tematic significance of any of the features described. 
The genus “Aplodontia” was established by Richardson in 1829, and, 
with varying orthography, has since been universally employed. Nor is it 
necessary to supersede it by Anisonyx of Rafinesque, 1817. This generic 
term, besides arising in a misunderstanding, was based upon the “ Burrowing 
Squirrel” of Lewis and Clarke, and is equivalent to Cynomys, of same author 
and date. It therefore becomes a synonym of Cynomys, as the type species, 
“Anisonyx brachiura”, also is of Cynomys columbianus (Ord). Rafinesque, 
however, added to his genus Anisonyz a second species, A. rufus, based ex- 
clusively upon the Sewellel of Lewis and Clarke, which causes Anisonyzx to 
be partly synonymous with the subsequent “Ap/odontia” of Richardson. 
The construction of the generic word has apparently given trouble, 
though there need have been none, had the rules for the formation of com- 
pounds from the Greek been duly considered. While some latitude is allow- 
able in such cases, unwarrantable liberties have been taken with this word 
The etymology is azAdos (contr. azAovs), simplex, simple, and ddovs, dens, 
tooth. The original form, Aplodontia, is clearly wrong in ignoring the aspi- 
ration of the initial Alpha, and is further modified arbitrarily by the suffixed 
syllables. As to the mode of joining the two words, in which three Omicrons 
come together, it may be observed: that the latter o in azAoos would, of 
course, suffer elision before the initial vowel of COovs; and then the former 
o, still coming before a vowel, would either be separated by a dizeresis over 
the second 0, or else be contracted with it into ov; so that the word might 
be written, with propriety, Haploddon or Haploudon, the latter perhaps 
being preferable, especially in view of the contracted form a@zAovs, in 
which the original is also found. But euphony has rightly so much to 
do with these formations that the former o in a@zAoos, as well as the 
latter, may be struck out before the 6 of ddovs (just as the latter o may 
be omitted before a consonant, contrary to general rule, as in azdAorys, 
compounded of a@zAcos and the abstract termination TNS, or in azAocyn- 
_ pe@rv), and the word be properly written Haplodon, the form I have 
adopted. In any event, Apludontia and Apluodontia are inadmissible, 
and Hapludon is objectionable from excessive contraction. In strictness, 
