PLACENTICERATID®. 233 
PLACENTICERAS SPILLMANI n. sp. Hyatt. 
Pl. XLVII, figs. 6-8. 
This species is founded upon a fragment, No. 4, in the collection of the 
Academy of Sciences of Philadelphia; but this is so distinct from any 
species of Placenticeras known to me that I venture to describe it here. 
This was in same tray with three fragments of Sphenodiscus labeled “Spill- 
man Coll. Loc. Mississippi.” 
The estimated diameter of the volution is 80 mm.; the actual ventro- 
dorsal diameter measured along the exposed septum from dorsal lobe to 
ventral lobe is 48 mm.; and actual transverse diameter is about 40 mm. 
through the dorsal lobe. - It has, therefore, a much stouter volution at the 
same age than its near allies, placenta or stantoni, and the venter is broad in 
proportion, being 9 mm in width, flat, and with low tubercles on either side 
about 14 mm. apart. The fragment is only the cast of the outer parts of 
two living chambers, and whether there were internal rows of tubercles 
could not be determined, but the sides have the flattened aspect of species 
that do not habitually have a median lateral row of tubercles. The sutures 
are closely similar to those of syrtale; they have broad, rather short, solid 
saddles, with short marginal saddles, the lobes narrow and broad, only at 
the apical ends. The outer part of the septum is more deeply concave than 
in placenta and the lobes and saddles are less complex in outline. There is 
a cast ot one chamber in the collection of Yale University, said to be from 
Burlington, N. J., with a similar broad venter, that may be the young of 
this species. The dorso-ventral diameter measured in same way as above 
is 24 mm., and transverse diameter is about 18 mm. There is also a cast 
from Musselshell Creek, Idaho, having a very broad venter. This belonged 
to a much older and larger shell with very different sutures. 
Locality: Burlington, N. J.; Mississippi. 
PLACENTICERAS ? TELIFER (Morton). 
Ammonites telifer Morton, 1834, Synop. Organic Remains, pl. 2. 
Ammonites (Placenticeras) telifer Whitfield, 1892, Mon. U. S. Geol. Survey, Vol. 
XVII, pl. 41. 
After examining the fragments of this species in the collection of the 
Academy of Sciences, Philadelphia, I am unable to determine with 
