MANTELLICERATID &. pie 
name. The reference to this genus accounts for the retention ot two lines 
of obsolescent tubercles on the flat venter between the large ventro-lateral 
spines. Schluetericeras laubei, described by Laube and Bruder in Ammoni- 
ten der Bohmischen Kreide® as nodosoides of Schliiter, and Schluetericeras 
michelobense occur in the Upper Turonian and are distinct in their forms, 
especially their large nodes and cost, and in their tendency to form definite 
channels on the venter, from either vielbanci or nodosoides 
SHARPEICERAS n. gen. Hyatt. 
This genus in its full-grown condition has very nearly the same form 
and characteristics as the neanic stage of Mantelliceras mantelli. There are 
eight lines of tubercles and the volution is compressed quadrate in section. 
The costa, are however, more evenly developed and do not bifurcate in the 
figures given by Sharpe. These characters are so marked and it is so 
plainly a phyloneanic form that it can not be placed in the same genus 
with Mantelliceras. Its characters in old age are unknown, but in the 
young, according to Sharpe, the costee are dichotomous from the line of 
tubercles on the umbilical shoulders. 
Type is Sharpeiceras laticlavium (Sharpe), figured on pl. 14 of his 
Fossil Mollusea of the Chalk of England (Pt. I, pl. 14). 
Sharp. schlueteri n. sp. Hyatt, described as Ammonites laticlavius by 
Schliiter in Cephalopoden der oberen deutschen Kreide’ is a Cenomanian 
species with less rapidly growing and less compressed volutions than in the 
English shell. Sharp. inconstans (Schliiter) is a more involute species of 
the same genus, having in its old age, if correctly defined by Schliiter, a 
volution precisely similar to that of the genus Acompsoceras. All of these 
belong to the Cenomanian 
ACOMPSOCERAS* n. gen. Hyatt. 
The type of this genus, Acompsoceras bochwmense, was described by 
Schliiter in his Cephalopoden der oberen deutschen Kreide,“ from the 
Cenomanian. In the adult stage, as described and figured. it has large 
fold-like costz on the lateral zones, with two rows of tubercles, one on the 
edges of a flattened venter and the other on the dorsal shoulders. These 
a Paleontogr., Vol. XX XIII, 1887, p. 229, pl. 25. ¢“Akouwos, unadorned. 
b Paleontogr., Vol. X XI, pl. 7. @ Paleontogr., Vol. X XI, pls. 1, 2. 
