May 16, 1884.] 
vary in size, from small pebbles no larger than a 
pea, to pieces an inch or more in diameter. They 
are of very irregular shapes, and of colors varying 
from light bluish gray to dark brown. When rubbed 
together, they emit the peculiar ‘naphthous’ odor 
which characterizes the South-Carolina phosphates. 
I collected and weighed the loose specimens from a 
square foot of surface: the weight was about two 
pounds, which would correspond to some forty-three 
tons to the acre. I was not able to ascertain whether 
the nodules were distributed through the whole of 
stratum no. 3, or whether they were confined to a 
distinct layer therein, though a number of sections 
were examined; nor can IJ as yet state the probable 
yield per acre in these nodules, but investigations are 
now in progress which will probably soon give some 
more definite information on this point. Associated 
with the nodules are great numbers of fossils, con- 
sisting of fragments of Nautili, of Ammonites, of 
Baculites, and other well-known cretaceous forms. 
In most instances these fossils are phosphatized 
more or less completely, in extreme cases to the 
extent of nearly obliterating the organic structure; 
and then the fossils resemble the nodules very closely. 
In addition to these are found many vertebrae, and 
other bones of saurians, and teeth of sharks, among 
which are some very large ‘pavement’ teeth. I have 
had several analyses made of the nodules, and find 
the content of phosphoric acid to be from twenty-five 
to thirty-eight per cent. 
4. Indurated ledge of light-colored sandy mar] from 
a foot to eighteen inches in thickness. This stratum, 
which is quite persistent, holds about ten per cent 
of phosphoric acid, the average of several analyses of 
samples taken from different localities. 
5. Loose whitish calcareous sands, passing down- 
wards into micaceous sands, and, at the depth of 
twenty to thirty feet below the ledge no. 4, passing 
into compact bluish sands, with considerable green- 
sand. 
The whitest sands, at the top of these beds, hold 
in places compact beds of small oyster-shells. The 
sands just below the ledge no. 4 are also impregnated 
with phosphoric acid; and, though no quantitative 
analysis has yet been made, the percentage, judging 
from appearance, cannot be less than ten. We have 
thus eighteen or twenty feet of strata charged with 
phosphoric acid; the content of this acid varying 
from ten per cent in the lower beds, to twenty per 
-cent in the greensand at the top. No analyses have 
yet been made of the beds which hold the nodules. 
Of the economical importance of this discovery it 
is as yet impossible to speak definitely, but, if the 
greensand beds can be made available, the yield will 
be very large; and the nodules may yet be found in 
compact masses instead of loose pebbles. 
It is probable that phosphate beds, in similar 
geological position, may be traced across the state; 
and already some greensands from Eutaw have been 
analyzed, and found to contain eight per cent of 
phosphoric acid. The following towns are situated 
near the line of contact of the rotten limestone and 
the underlying sandy strata: Tuskegee, Montgom- 
ery, Vernon, Autaugaville, Burnsville, Summerfield, 
Hamburg, Greenesboro, Eutaw, Clinton, Pleasant 
Ridge, Bridgeville, and Pickensville in Alabama, and 
Columbus, Aberdeen, Cotton-gin Port, Guntown, 
Baldwin, Booneville, Rienzi, and Farmington in 
Mississippi; and it is well worth while to search 
along this Jine for other occurrences of phosphates, 
especially where the saurian bones and sharks’ teeth 
are abundant. EUGENE A. SMITH. 
University of Alabama, May 3. 
SCIENCE. 
87 
A blind fish from the Missouri River. 
An old fisherman on the river brought me yester- 
day an anomaly which none of his craft had ever 
seen before. It was ashovel-nosed sturgeon (Scaphi- 
rhynchops platyrhynchus (Raf.) Gill), which ex- 
hibited on the surface no sign whatever of eyes. 
These were concealed by a complete overgrowth of 
the prickly skin, which, on casual examination, 
differed in no respect from its normal appearance 
elsewhere. Upon very close inspection, however, a 
slight indentation, like a small pin-prick, was found 
to mark the place where one eye ought to be, but it 
did not penetrate the skin; and even this could not 
be detected over the other eye. 
I skinned and mounted the fish, and, after skin- 
ning, removed the eyes from the inside through the 
mouth and gill openings. In one of these I could 
detect nothing abnormal. The other was without 
the crystalline lens, though the cornea and iris were 
apparently in place when I took it out; but, as it was 
removed with considerable difficulty, the lens might 
have been pressed out in the process. The first-men- 
tioned eye was taken out with more care and less dif- 
ficulty, and was entirely uninjured. 
The sturgeon was normal in every other respect, 
twenty-five inches long to the tail, and showed no 
sign of injury to account for the monstrosity. It was 
in as good physical condition as others of its kind, 
so far as I could see, and seemed to have labored 
under no unusual disadvantage in its struggle for exist- 
ence. The alimentary canal contained several insect 
larvae, the only contents that could be recognized. 
Most of these were so far digested as to be beyond iden- 
tification. One, about an inch long, had rudimen- 
tary mouth-parts and no legs, and might have been a 
dipterous larva. Two fragments resembled the larva 
and pupa of some Lampyridae. Another was a 
lamellicorn beetle larva, probably of Lachnosterna 
fusca Frohl. 
As the habit of this sturgeon is to plough in the mud 
for its food, and to use its tactually sensitive barbels, 
with perhaps the soft skin covering the under surface 
of its shovel-nose, as a substitute for sight, it can 
have but little use for eyes: hence they might about 
as well be covered with skin, or become rudimentary, 
as those in the blind fishes, cray-fishes, etc., in 
Mammoth Cave and in certain subterranean streams 
and ditches, and for the same reason. 
The eyes of this species are very small for its size, 
and especially small as compared with the eyes of 
most fishes. So the mole has its eyes reduced to a 
mere speck, which doubtless, as Mr. Huxley says, 
‘have no functional use.’ It seems, therefore, not 
unreasonable to suppose that this unfortunate stur- 
geon’s closed and sightless eyes may be only a pro- 
phetic instance of the fate which awaits all that 
belong to this species, and that even the normal eye 
is already considerably advanced in the process of 
abortion. S. H. TROWBRIDGE. 
Glasgow, Mo. 
The use of the method of rates in mathemati- 
cal teaching. 
In regard to the communication of Professor John- 
son, in your issue of April 18, p. 473, he admits that 
he is puzzled by the form of the questions which he 
assumes I put into the mouth of my students. I 
had no intention of puzzling him; and, in regard to 
the questions, they were real samples of those pro- 
posed by students from time to time. Not that all 
were asked by one student, or during one discus- 
sion, nor limited to those given. 
