Hevieio of Recent Geological Literature. 255 
for the popular mind to be enthused with visions of mineral 
possibilities that do not exist, or at least have not been practicably 
demonstrated. The quantity of platinum found in a specimen of 
inexact locality was a single fragment less than a pin head — suffi- 
cient however to justify a scientific investigation. The same can 
be said of the tin ore, which so far as yet known exists only in 
cmantities sufficient for mineral curiosities. The experience of 
hundreds in Mississippi, Alabama, Arkansas and Texas, has 
shown the commercial impracticabilit}^ of the lignites for fuels, 
while the Tertiary greensands fully studied by Hilgard have never 
been adapted to agriculture. There are many valuable materials 
in Texas however for economic development. Rich chalk and 
Cretaceous marls and greensands, gypsum, and probable phos- 
phate beds occur. Her vast coal fields have never been looked 
into by a competent expert, except in the interest of private par- 
ties. Superb building stones and structural material await devel- 
opment, while the conditions for manufacturing improved artificial 
Portland cements — such as America is now entirely dependent 
upon Europe for — exist in the chalk districts of Texas in marvel- 
ous quantities. In the rarer minerals, the state is exceedingly 
rich, but in nearly every case where investigated these have proved 
of little quantity, except in the Trans-Pecos region where there 
are undoubtedly valuable silver districts. 
In the small Paleozoic area of the Burnet district from which 
the overlying Cretaceous beds have been eroded there is a greater 
diversit3'of rare minerals than in any spot in America, over thirty 
of the known chemical elements including many of the rarer ele- 
ments such as yttrium, thorium, etc. , having been found at a 
single locality (Barringer hill), by Dr. Edgar Everhart of the 
State University. 
The iron and mangenese ores of the state are of the greatest 
value, and are now being rapidly developed by private capital. 
KEVIEW OF RECENT GEOLOGICAL 
LITERATURE. 
Pevisomic Plates of the Crlnoids. By Charles Wachsmtttb and 
Fijaxk 8PBTNGEB. (Proc. Acad. Nat. Sri.. lMiila.. 1890, with two 
plates.) The recent progress In crinoid morphology has been somewhat 
phenominal. Towards abetter understanding of the phylogenetlc 
