ENGONOCERATID 2. 167 
living chamber is about one-half of a volution and is nearly complete. 
The venter broadens out, and this specimen seems to be outgrown, judging 
from the approximation of the last three septa. The sutures are similar to 
those of the preceding, but the seventh saddles are bifid. 
Specimen from locality 1545, Chalk Mountain, near Glenrose, diameter 
of volution 50 mm., partly estimated, has seventh saddle on the right side 
bifid; all others external to this entire and phylliform, except, of course, first 
lateral. This cast shows plainly that what is here counted as the second 
lateral is an adventitious saddle derived from division of the first lateral 
saddles, and the first lateral lobe is also an adventitious inflection arising 
from a primitive marginal of the first lateral saddle. 
A fragment from the Goodland limestone, Choctaw Nation, about 100 
miles east of Preston, Tex., is considerably worn, but apparently of this 
species. The volution is 33 mm. from line of involution to venter and:is in 
gerontic stage, the last six sutures overlapping. The venter is also rapidly 
broadening, the gerontic tubercles and costz are larger than usual, and the 
venter is more asymmetrical or zigzag in outline. There are nine saddles 
visible, and the seventh and eighth are bifid; the outlines of others are 
entire. The lobes, owing probably to attrition, are all entire. 
A specimen in the United States National Museum, No. 22643, from 
locality No. 973, near Cerrogordo, Ark., has a combimation of characters 
which appears to unite serpentinum with pierdenale. he sutures have the 
broad, short saddles with flat bases, like those of serpentinum from near 
Gainesville, but the size of specimen, nodes, and aspect are similar to the 
typical fossils of prerdenale. The surface is worn down somewhat in this 
east, and probably these resemblances may be due to this cause. This cast 
is 91 mm. in whole diameter; transverse diameter estimated at 20 mm. 
A cast in the Museum of Comparative Zoology from Towash, Hill 
County, Tex., is 56 mm. in diameter; the outer volution is 27 mm., the 
umbilicus 8 mm., and the opposite part of same volution from line of 
involution to venter 21 mm. This is an outgrown specimen, the last six 
sutures overlapping those preceding, while in ephebic stage they are 
separated by a distinct interval. 
There are the usual lines of tubercles, and the cost on the outer part of 
the volution become very decided, as in other aged specimens. The venter 
is at first narrow, but this becomes much broader at the same time that costz 
