200 PSEUDOCERATITES OF THE CRETACEOUS. 
PLACENTICERAS SANCARLOSENSE n. sp. Hyatt. 
Pl. XXX, figs. 1-3; Pl. XOXOXT) figs. 1, 2. 
This is represented by a series of specimens in collections made by 
Stanton and Vaughan that fade into true guadalupe. 
The typical forms differ in having smaller tubercles, the compressed 
stage is more prolonged and the ephebic volutions are never so stout nor 
the venter so broad as in guadalupe. The stage in which the venter is 
broad and bounded by the second line of nodes and similar to that of 
guadalupe. is short and is often distinetly confined to the anagerontic 
substage. Some of the specimens of this form are very closely similar to 
P. syrtale. This last species has, however, so far as known, no stage in 
which the venter resembles that of guadalupe, i. e., in which the venter 
becomes broadened out while the ventral lines of tubercles and the lateral 
nodes are still preserved in nearly their full development. This form is 
obviously an exact parallel with the P. pseudosyrtale said to be found at 
Fort Worth,” but from this it is separable by the involution which is more 
considerable and follows the inner line of tubercles. There are dwarfs 
belonging to this species which have more pronounced tuberculations than 
Placenticeras newberryi, but these approximate very closely to the specimens 
from Presidio del Norte, and show that these last are really another grade 
of modifications having the same general tendency. 
Locality: San Carlos, Presidio County, Tex. 
Age: San Carlos beds, Upper Cretaceous. 
PLACENTICERAS SANCARLOSENSE variety PSEUDOSYRTALE Hyatt. 
JEG ROLO200ls Jal DOO GUN ies Ile 
The type of this variety is a well-preserved cast 200 mm. in whole 
diameter. The last volution from lines of involution to venter, although 
much affected by senile contraction, is 80 mm. and the same volution oppo- 
site is 65 mm. The ventro-dorsal diameter is 73 mm. about half way the 
length of the living chamber, and the transverse diameter is 53 mm., avoiding 
the tubercles. The same ventro-dorsal diameter at last septum, taken 
always from line of involution to venter, is 63 mm. and the transverse, 
avoiding the tubercles, is 48 mm. The tubercles of first inner row alternate 
a See note on p. 202. 
