202 
Transactions Texas Academy of Science. 
Os ANN, A. 
in the field, on the other, are aibsolutely necessary for the right understand- 
ing of rocks. (If, notwithstanding, some unconnected and incomplete notes 
on the subject are given, it is done in accordance with the order of the 
director of the Greological Survey, with a view to giving an idea of the 
great variety, especially of igneous rocks, in Western Texas, and for the 
reason that no petrographical description of them has yet been given. 
‘‘The geological material collected in Western Texas can be divided into 
four groups: i, Igneous Rocks; 2, Orystalline Schists; 3, iSedimentary 
Rocks ; Ore Specimens. 
“Only 'the first group will be described in this report. Of crystalline 
schists there are only a few specimens from ‘Mica Tanks’ in the Van Horn 
Mountains. They consist of gneisses (muscovite gneiss and muscovite and 
biotite-bearing gneiss ) , mica schists and amphibole gneisses in transition 
to amphibolites. These rocks are not yet studied under the microscope.” 
)P. 123. 
309. 
Melilite-Neplieliiie^Basalt and Nep'^ieline-Basaiiite, from South- 
ern Texas. 
Jour, of Geology, Yol. I, 'No. 4, pp. 341-346. Chicago, 1893. 
“These basaltic rocks were collected by Professor Bumble and Mr. Taff 
in Uvalde county. Southern Texas. On the Geological Map of the United 
'States, compiled by O. H. Hitchcock, 1886, there are two of the localities 
marked near the boundary of the Cretaceous and earlier Tertiary forma- 
tion between 99° and 100° longitude, and on the 29th degree of latitude. 
According to the statement of Professor Bumble, one part of the rocks 
appears in dikes in the upper portion of the lower Cretaceous formation, 
while the other forms hills and buttes. Upon microscopical examination 
it is evident that the specimens collected belong to two different groups 
of rocks. The mierosoope shows that those occurring in dikes consist of 
typical melilite-bearing nepheline-basalt, while those making up hills and 
buttes are nepheline-basanites tending toward phonolites in composition.” 
P. 341. 
A description of these rocks, which were subjected to a microscopic 
examination, follows. 
“A microscopical examination of the basaltic rock from Pilot Knob, near 
Austin, Travis county, was made for the purpose of comparison with the 
rocks from Southern Texas just described. The rock was found to be a 
nepheline-basalt porphyritic With numerous phenocrysts of olivine. The 
fine grained ground mass consists essentially of augite-crystals cemented 
together by non-individualized nepheline in very small amount.” P. 346. 
Noticed in Am. Naturalist, \ ol. 28, pp. 799-800, Sept., d894. 
310. Owen, J. 
Notes on tlie Geology of the Kio Grande Valley. 
Geologieal and Scientific Bull., Yol. 1, No. 2. Houston, June, 
1888. 
“It does not appear to be generally knotwii that along 'the valley of the 
