Marcu 14, 1884.] 
examined by Mr. R. Ellsworth Call, who reports the 
following species: Aphaerium dentalum Haldeman, 
Pisidium ultramontanum Prime, Helisoma trivolvis 
Say, Granulus vermicularis Gould, Limnophysa 
bulimoides Lea, Carnifex Newberryi Lea, Valvata 
virens Tryon. 
The mingling of the blackened and mineralized 
bones of horses, camels, elephants, edentates, etc., 
with the shells enumerated above, presents a puzzling 
association of extinct tertiary(?) mammals with quan- 
tities of shells of living species, which we had hoped 
Professor Cope’s studies would elucidate. 
The presence of ‘ worked flints,’ mingled with the 
fossil bones, is a matter of but little significance; as 
the bones occur on the surface, and might have had 
arrow-heads, etc., scattered among them at a very 
recent date. There is no evidence that the fossil 
animals, and the people who chipped the flints, were 
contemporaneous. 
The valley of the Warner Lakes is referred to as a 
‘fractured anticlinal.’ Again, the same expression is 
used in describing Silver Lake. We believe, how- 
ever, that geologists familiar with the progress of ex- 
ploration in the Far West during the past ten years 
would class these basins as monoclinal valleys, of 
the Great Basin type. The Warner valley has a 
profound fault along both the eastern and western 
borders, and is enclosed to a great extent by lofty 
fault-scarps. 
The Abert Lake basin also owes its formation to 
displacements. The lake occurs at the base of agreat 
fault-scarp, forming a cliff two thousand feet high, 
and covers the depressed edge of a thrown block. 
In the passage relating to Abert Lake (p. 138), the 
reader is left in doubt as to whether the lake, or the 
Chewaucan River, abounds introut. Later, however, 
three species of fish are credited to Abert Lake. My 
own experience has been, that trout are abundant 
in the river, and absent from the lake; although they 
perhaps could exist in the latter in the immediate 
vicinity of the mouth of the Chewaucan River 
(frontiersmen who are familiar with the lake say that 
it is uninhabited by fish). During my own exami- 
nation I found its waters swarming with ‘brine 
shrimps’ and the larvae of insects, but never saw a 
trace of piscine life. Its waters are strongly alkaline, 
and utterly unfit for culinary purposes. In its phys- 
ical properties the water of Abert Lake resembles 
the brines of Sumner Lake (Oregon), Moro Lake 
(California), and the soda-ponds (near Ragtown, 
Nev.), all of which are too strongly alkaline to be 
inhabited by fishes. It is not evident on what au- 
thority Professor Cope ascribes a fish fauna to this 
lake, as on p. 138 it is stated distinctly that he did 
not get a near view of it. 
From a study of the geographical distribution of 
the fishes in the lakes of the Great Basin, Professor 
Cope has found that the larger fishes inhabiting the 
lakes in northern Nevada and south-eastern Oregon 
are different from those of the lakes of the Bonne- 
ville basin. This is an interesting determination; as 
! See ‘ Basin Range structure,’ Geol. of the Uintah Moun- 
tains, Powell, p. 16. 
SCIENCE. 
323 
the former basins were mostly without outlets dur- 
ing the quaternary, while the latter became tributary 
to the Columbia. 
The effect of alkalinity on the growth of fishes has 
been noted by Professor Cope to some extent, and is 
evidently a study that might lead to interesting geo- 
logical conclusions. The comparison of the faunas 
of Pyramid and Tahoe lakes would perhaps show the 
effect of salinity and alkalinity on the species of 
fishes which probably inhabit both lakes. Pyramid 
Lake, it will be remembered, is supplied almost wholly 
by the Truckee River, the outlet of Lake Tahoe. 
Before concluding that ‘all the species of Pyramid 
Lake are peculiar to it, excepting Catostomus tahoen- 
sis,” it would be desirable to compare its fishes with 
those of Walker Lake. As these two lakes are quite 
similar in chemical composition, and both occur in the 
Lahontan basin, it seems probable that their abun- 
dant faunas would be found nearly identical. One 
species of trout, at least, seems to the writer, from 
superficial examination, to be common to the two. 
The second part of Professor Cope’s paper is de- 
voted to the description of the fossil fauna of ‘ Idaho 
Lake.’ This lake existed in eastern Oregon and west- 
ern and southern Idaho during pliocene time. No 
body of water represents it at present; and the fish- 
remains found in its sediments differ from those of 
the Oregon basin, both recent and fossil. The extent 
of this ancient lake is not known. Its sediments are 
named the ‘ Idaho formation,’ but no typical exposure 
is described or in any way indicated. Even the lo- 
cality at which the fossil bones were collected is, for 
some unstated reason, withheld. This method is to 
be regretted; as Professor Cope does not stand alone 
in making geological divisions on purely paleonto- 
logical grounds, without attempting to describe or 
locate the formations named. If this practice is per- 
sisted in, it can only lead to confusion. 
Of the twenty-two species of fossil fishes described, 
eight are new. Besides these, the sediments of the 
Idaho Lake have furnished three species of crawfish 
which were reported by Professor Cope some years 
since. The mollusks, it appears, have already been 
described by F. B. Meek. Both the vertebrate and 
invertebrate fossils of the formation determine it to 
be lacustrine and fresh. 
Although we have ventured to take exception to a 
number of statements in the paper under review, yet 
we welcome it as adding materially to our knowledge 
in a field that had previously been but little studied. 
ISRAEL C. RUSSELL. 
Washington, D.C. 
THE DEFINITION OF MEAN SOLAR 
TIME. 
THE proper definition of mean solar time appears 
to me a very simple matter, and to have nothing 
arbitrary about it. The mean sun is merely an 
imaginary body which is supposed to move uniformly 
1 Paper by Prof. J. C. Adams of Cambridge, at the December 
meeting of the Royal astronomical society. From The observa- 
tory, February. 
