98 PSEUDOCERATITES OF THE CRETACEOUS. 
one. The remaining saddles are very short, broad, and more or less 
phylliform. The fifth is entire with exception of minute marginals; the 
sixth is trifid without secondary marginals; the seventh and eighth are 
unsymmetrically bifid; the ninth and tenth are entire and phylliform. The 
eleventh saddle passes across the lines of involution and forms the seventh 
saddle of the dorsum. The corresponding saddles on the right side are 
quite distinct in detail, but of the same number and similar in general 
aspect. However, the fifth and sixth laterals are unsymmetrically trifid 
with secondary marginals, showing that they were on the road to the 
quadrifid type,“ and the seventh is bifid. The remaining saddles are shown 
on the same side at an older stage. The eighth, ninth, and tenth were 
phylliform and entire; the eleventh was entire, and situated on the line of 
involution. The lobes on the left side were as follows: The first laterals 
were merely marginals on the first lateral saddles, the first corresponding to 
the first saddle, as reckoned above, the second and third progressively 
deeper. The third, although it was apparently trifid in type, was 
subdivided by a very long, slender, and peculiar marginal saddle coming 
from opening of fifth lateral saddles. The fourth, fifth, sixth, and seventh 
laterals were broad at the tops and had pointed small marginals as in some 
other more primitive species. The eighth, ninth, and tenth had more 
unequal serrations and were narrow at the tops. eae 
The adult sutures were exposed on an inner volution and exhibited, as 
I anticipated, more overlapping than in the gerontic stage, owing to the 
greater length and development of the second and third lateral saddles. 
This is an instructive case because, as a rule, the overlapping is greater in 
the gerontic stage than in the ephebic. In the extreme gerontic stage, 
when the decrease in length of the saddles and lobes is greatest, the 
approximation of sutures causes overlapping, notwithstanding this decrease. 
But in a prolonged gerontic stage the relative decrease in length of lobes 
and saddles may sometimes, as in this case, where septa are not much closer, 
cause sutures to appear wider apart than in the ephebic stage. 
The adult sutures had very much the same outlines as in the gerontic 
stage described anove, but there was a slight overlapping along the entire 
1 
suture. 
_©This shows a variation between the two sides that is interesting, and it must also be noted that 
there is a slight overlapping on this side, owing to the greater length of the fifth and sixth saddles. 
