80 PSEUDOCERATITES OF THE CRETACEOUS. 
Meek’s figure and also sixth, seventh, eighth, and mth, while the fourth 
and fifth are trifid. The ninth lobe is of the primitive trifid type; those 
interior to this were not seen. The first lateral saddle is unsymmetrically 
trifid, the second to the fourth more symmetrical but rather irregularly 
quadrifid, the fifth and sixth trifid, the seventh, eighth, and ninth bifid, 
with broad phylliform bases, the tenth entire. The remainder, probably 
at least two more, were not seen. 
The lines of the sutures are quite distinct and are separated by a 
considerable interval to the third lateral saddle in the older septa, and in 
the younger septa this separation is maintained until the innermost lines 
of bifurcated saddles are reached. 
A fragment from Fox Hills, coilection Museum Comparative Zoology, 
No. 397, shows that this species must have attained a much larger size than 
the specimen described above. ‘The sutures are visible on this fossil, the 
partly estimated breadth of the sides being 180 mm, the transverse 
diameter through the zone of involution at the fifth pair of dorsal and 
eighth pair of lateral saddles being 65 mm. There are seven pairs of 
divided saddles. The first laterals are quadrifid on right side and bifid on 
the left side, the second to the fourth are quadrifid on both sides, and the 
fifth to the seventh, bifid on both sides. The next or eighth pair are entire. 
The volution was absent beyond this line. The outlines are obviously 
similar to those of S. lenticularis var. splendens, and the dorsal including 
the antisiphonal lobe also resemble that variety and are more cross-shaped 
than in Pl. IX, fig. 8, which gives the dorsals of S. lenticularis variety 
mississippiensis. here are three layers present in the shell. 
A fragment of a cast (Pl. VI, figs. 3, 4), collection Yale Museum, 
No. 200, from Birmingham, N. J., from the Lower or Middle Greensand 
Marls, Upper Cretaceous, evidently in its ephebic stage, shows sutures that 
are quite different from those of any other form. The venter is destroyed 
except in one spot, but this is sufficient to show it to he solid and acute. 
The volution is stouter than in typical /obatus or lenticularis. ‘The actual 
diameter from line of involution to venter is 61 mm., and it was probably 
a few millimeters deeper; the transverse diameter here is 25 mm., this 
being also a few millimeters shorter than the actual diameter. 
The ventral lobe is broad, and it is also evident that the siphonal sad- 
dles are not bordered internally by prominent marginal saddles. ‘There 
