205 
typical olivine basalt. (Pl. II, fig. 2.) The principal minerals are 
labradorite, olivine, a green augite, and magnetite. ‘The trachytie tex- 
ture is very pronounced in the thin section. Zonal structure is very 
common in the feldspars and an occasional twin in the shape of an X can 
been seen. 
As we travel up the slope to the divide we find the lava becoming 
more porous and lighter in color, until in the neighborhood of the lime- 
stone it is practically a scoria. From the rather limited observations 
the writer was able to make here, it appears that these flows probably 
poured out over the country from Talim, leaving a small peak of lime- 
stone in part exposed. 
THE LIMESTONE. 
The limestone, which is the tomb of Orbitoides, is exposed in a cliff-like 
mass, a hundred feet or more in height, and seemingly dipping steeply 
to the east, though this may prove to be not true bedding, but some 
secondary structure. In color the rock varies from a light cream to a 
dirty, bluish-gray. The lighter and denser portions are more fossil- 
iferous. On microscopic examination it was found to contain Orbitoides, 
differing somewhat from the forms described by Messrs. Newton and 
Holland, and which the writer proposes to call Orbitoides richthofeni, 
some fragments of Operculina complanata? Def., and a very imperfect 
form which is suggestive of Lithothamnium ramossisimum Reuss. 
DESCRIPTION OF SPECIES. 
The genus Orbitoides differs in one radical respect from Nummulites, 
namely, in that the chambers of Orbitoides are arranged concentrically 
and not spirally as in the latter form. All the specimens we have found 
belong to the Lepidocycline group, this terminology referring to the 
lozenge-shaped chambers along the median plane. It is probable that 
more than one species is represented, and there is a great difference in 
the size of some of the specimens. 
Orbitoides richthofeni sp. nov. 
(PI. I, fig. 1.) 
The type of this is the largest specimen found in this locality, but 
unfortunately it is not a perfect one. The one we have depicted by 
Plate I, fig. 1, has lost a portion at each extremity, but if restored 
would measure in the neighborhood of 36 millimeters in length and 8 
millimeters in width at its thickest portion. These tail-like appendages 
are very characteristic and give to the whole the appearance of the head 
of a pick. 
The initial chamber is not shown, or it is exceedingly small. Instead, 
along the median plane are developed lozenge-shaped chambers arranged 
at right angles to the long axis of the form and continued out into the 
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