SPHENODISCID&. 15 
zygous entire saddles and three pairs of similar lobes. The globular first 
stage had been lost out of this fragment before it came into my hands. The 
sutures have five columns of bifid saddles on the right side and six on the 
left side when the volution is about 10 mm. broad. The suture figured 
was taken from a volution about 12 mm. broad transversely (P!. IX, fig 5). 
The dorsal sutures are of the same age, but were drawn on a larger scale 
by mistake and have been separated as a distinct figure on that account. 
There is an interesting small specimen in the Academy of Natural 
Sciences, Philadelphia, said to be from near Santa Fe, N. Mex. In this 
museum and in the United States National Museum there are fragments of 
volutions of large size having very broad, coarse, low folds on the outer 
half of the sides; these may belong to this species. The largest is 102 mm:- 
from line of involution, which was not wholly complete. The sides are 
rather gibbous, the venter still subacute, although not so sharp as in earlier 
stages. Through the thickest part about 34 mm. from keel the transverse 
diameter is 51 mm The absence of tubercles at all ages was completely 
demonstrated in this species. The concave zone found along the inner half 
of the older volutions in S. plewrisepta and lobatus was not present in this 
species, although low, fold-like, arcuate costze were found as figured by 
Meek in older stages on the outer parts of the whorls. 
Locality: Moreau River, South Dakota; Rock Creek, Wyoming; Santa 
Fe, N. Mex. 
Age: Fox Hills group, Upper Cretaceous. 
SPHENODISCUS LENTICULARIS variety SPLENDENS Hyatt. 
Pl. VILL, figs. 3-7. 
A young fragment broken out of an older volution is in the form of 
a cast, but with the sutures and septal partings beautifully marked. It 
has the usual ax-like venter of its congeneric forms, with fold-like, arcuate, 
very obscure costa showing on the outer parts of the sides. The extreme 
acuteness of the venter shows that this species had a solid keel. The first 
to the sixth saddles on the right side and the first to the fifth on the left 
side in the smaller cast and also in the larger are bifid. An observer 
seeing the young on one side and the older fragment on the other would 
be apt to consider this lateral ditference as a distinction due to age. The 
