210 PSEUDOCERATITES OF THE CRETACEOUS. 
opposite in old age and are sometimes connected by a ridge, so that the 
venter is serrated. The inner line of tubercles recedes in this stage, as in 
specimen figured by Meek. 
The sutures have shorter, stouter saddles than those figured by Meek, 
and are more like those of P. syrtale. In the first lateral saddles especially 
they are more deeply cut into by the lobes that broaden out apicad, and the 
other lobes and saddles are like those of itercalare, as figured by Meek. 
The resemblances to syrtale occur more markedly in old age, when the 
body of the first lateral saddles loses the thread-like tenuity of the ephebic 
stage and becomes thicker. All the saddles do not show these changes 
equally. This last specimen has enabled me to make connections with No. 
18975 U.S. National Museum, from the Upper Missouri, which is a nearer 
approach to syrtale. The inner nodes on this last are about the same, but 
are not partly buried by the involution and make their appearance some- 
what earlier in the neanic stage. The outer line of tubercles are larger and 
the venter is broader. The sutures, however, and the proportions, ete., of 
the volutions are about the same. Lastly there is a fragment in same 
collection, locality No. 1720, 5 miles southeast of Harpers Station, Laramie 
Plains, Wyo., that no one would think of separating from syrtale by the 
external characters. The diameter is 94 mm., and the specimen has the 
same wide umbilicus, stout volutions, prominent nodes, and sharp ventral 
tubercles as that species. The sutures, however, although the specimen is 
so small, are almost as excessively complicated in outlines as in Meek’s 
figure, although this was taken from a much larger volution. 
One specimen, No. 9735, U.S. National Museum, from Ponil Canyon, 
New Mexico, has characters just intermediate between P. intercalare and 
P. placenta. .Vhe young and full ephebie stage has the form of the stouter 
specimens of intercalare with three rows of tubercles. The two outer rows 
are, however, more delicate than usual in intercalare, especially the median 
lateral ones, which are very small and widely separated as in P. placenta. 
Unfortunately the last of the ephebic and the first part of the gerontic 
stages are missing, but the parts left show similarity with the old age of 
P. placenta and intercalare. The venter does not broaden out except very 
slightly while becoming rounded as it does on the third quarter of the 
outer volution. The sides lose the abrupt elevated umbilical shoulders and 
become evenly convex, but the involution continues to follow the umbilical 
