306 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxiv. 
name Ostrea virgata., which has a lower valve, with sculpture quite 
similar to that of C. niunsonl^ but examination of the original speci- 
men, now in the museum of Yale University, shows that it is a true 
Odrea with a smooth upper valve and not at all related to C mmisfmi. 
Localities and position. — HilTs figured types came from Bel ton, 
Texas: those discussed bj^ Cragin as part of a supposed I/ij)jnn'ites., 
from Bartons Creek, near Austin, Double Mountain, in Stonewall 
County, and Big Springs, Howard County; additional specimens in the 
Texas State collection are labeled "Cooper Mountain, Kent Count}";" 
the specimens now figured are from Nolands River at Belton, and from 
the bed of Bartons Creek, near the stone bridge 2 miles from Austin, 
where the species is abundant; a few additional specimens are from 
near Kickapoo Springs, on the west fork of Nueces Kiver, from High 
Bridge, on Pecos River, and from Bluff Creek, about 25 miles west of 
Waco, the latter collected by Mr. elohn K. Prather. The species is 
confined to the Edwards or "Caprina" limestone, in the Fredericks- 
burg division of the Comanche series. Precise correlation of the hori- 
zon with the European section will not now be attempted, but it is 
certainly much older than the Turonian. 
CHONDRODONTA GLABRA, new species. 
(Plate XXVI, figs. 1-3.) 
Shell rather large, flat, or sometimes variously ))ent; lower valve 
gently convex; upper valve concave, closely conforming to the curva- 
ture of the attached valve; beaks inconspicuous, submedian, scarcel}' 
at all deflected laterally, with a very small area of attachment on the 
lower valve; surface of both vah'es .smooth with only irregular lines of 
growth; internal characters as described for the genus, the hinge plate 
of the lower valve showing also one or two obscure shallow grooves 
in advance of the chondrophore. 
An average specimen measures 117 mm. in length, QS mm. in greatest 
breadth, and 10 nun. in convexity of the two valves united. The 
general ha))it of the shell is very similar to that of C. niunsoni and the 
structure of the hinge is essentially the .same. The smooth surface at 
once separates it from that species. It also appears to be somewhat 
more regular in form and more nacreous in texture. 
Locality and position. — The types (five specimens) were collected b}- 
the writer in 1895 at a quarry one mile east of Kerrville, Texas, where 
the species is abundant, associated Avith Monopleura in a thin band near 
the middle of the limestone then quarried. The horizon was thought 
to be the upper part of the (xlen Rose, and therefore considerably older 
than the horizon of ('. munsoni, though I did not have the opportunity 
to study the stratigraphy of the neighborhood in detail. 
