Juny 2, 1897.] 
plished, but he says it is so long ago he no 
longer remembers the course of reasoning 
he followed at the time. 
I assume that Capt. C. E. Dutton, who 
at Powell’s request took up and completed 
the latter’s Colorado cafion geology, is likely 
to have voiced his matured opinion on this 
point. In his paper on the Grand Cafion 
(2d Ann. Rep. Director U. 8S. Geol. Sur- 
vey, p. 62), in treating of the persistence of 
rivers, Dutton gives a most graphic descrip- 
tion of the course of the Green river in its 
passage through the Uinta mountains. In 
spite of the fact that he places Horseshoe 
Cafion on the south instead of on the north 
flank of the mountains, it is evident that he 
must have read Powell’s description, for he 
uses not only his metaphor about the ‘right 
of way,’ but also the simile of the saw pre- 
serving its position while the log moves. 
Whether consciously or not, however, he 
certainly does not agree with Powell’s hy- 
pothesis, for he says in conclusion : ‘“What 
then did determine the situations of the 
present drainage channels? ‘The answer is 
that they were determined by the configura- 
tion of the surface existing at or very soon 
after the epoch of emergence. Then, surely, 
the water courses ran in conformity with 
the surface of the uppermost (Tertiary) 
stratum.” 
Dutton elsewhere states more definitely 
that the course of the Green or Colorado 
river south of the Uinta mountains was de- 
termined at the close of the Eocene. If this 
is correct, I was probably wrong in assum- 
ing that the Green river first found its way 
across the Uinta mountains after the Wyo- 
ming (Bishop’s Mt.) conglomerate had 
been deposited, because I found undis- 
turbed remnants of this formation on either 
side of the river, both on the north and 
south flanks of the mountains and at such 
elevations that, if the beds were continued 
across the intermediate country on the same 
level, they would completely cover that por- 
SCIENCE. 
21 
tion of the mountains through which the 
Green river now runs. I have for a long 
time been hoping and still hope that some 
other geologist may make a more thorough 
examination than I was able to at that time, 
and determine the nature and extent of 
this singular formation, which has never 
been satisfactorily accounted for. What- 
ever may be the outcome of such an ex- 
amination, it would seem proper that the 
antecedent origin of this river should be 
held in abeyance until some positive evi- 
dence of it can be furnished. 
S. F. Emmons. 
U.S. GEOLOGICAL SURVEY. 
ZOOLOGICAL NOTES. 
THE SCIENTIFIC NAME OF THE VISCACHA. 
One of the best known mammals of the 
pampas of the Argentine Republic is the 
viscacha, now usually called Lagostomus 
trichodactylus. Unfortunately this name 
proves to be untenable, but in order to 
show that such is the case it will be neces- 
sary to refer briefly to the history of the 
species. The animal was first described in 
1801, by Azara, who considered it identical 
with Cavia acuschy of Gmelin, which is now 
known to be an entirely distinct species. 
Rafinesque, in 1815,* proposed the genus 
Viscacia, apparently without description, so 
that his name is not entitled to recognition. 
One year previous, in 1814, according to 
Waterhouse (Nat. Hist. Mamm., Rodentia, 
1848, p. 213), a living viscacha was placed 
on exhibition in London,} where it was 
examined by Blainville and Cuvier. Blain- 
ville soon after described the species as 
Dipus maximus.{ Some years later the same 
animal came into the possession of Brookes, 
a member of the Linnzan Society of Lon- 
don, who gave a full description both of its 
* Analyse de Ja Nature, 1815, p. 56. 
+ Burmeister states that there were two. 
¢ Nouv. Dict. d’Hist. Nat., nouv. éd., XIII., 1817, 
pp. 117-119. 
