112 PSEUDOCERATITES OF THE CRETACEOUS. 
are exactly like those of Pulchellia. In the aspect of these ornaments and 
in the convex venter with its nascent keel or raised line there is also a close 
resemblance to Roemeroceras and even to Buchiceras. But Schliiter dis- 
tinctly states that this is not a keel “und der Sipho driickt die Mittellinie 
des Bauches etwas in die Hohe, ohne dass jedoch ein eigentlicher Kiel 
entstiinde.” In old age the sides become smooth and the venter rounded, 
and all traces of tubercles and coste are lost. The sutures have a decided 
similarity to those of Sharpeiceras inconstans, and, as stated in noticing that 
species, the older stages of this species are similar to those of bochumense, 
while the younger ones, including the ephebic stage, have the character- 
istics of Sharpeiceras. This implies genetic connection with that genus, 
and if confirmed by further observation, settles the origin of the group. 
The young are not known, and until these are known it is, of course, ques- 
tionable whether the affinities for Sharpeiceras are as close as is assumed 
here. 
Acompsoceras essendense (Schliiter), described in the work quoted 
above, and also from the Cenomanian, is another species of the same genus. 
ACOMPSOCERAS RENEVIERI (Sharpe). 
Ammonites renevieri Sharpe, 1856, Foss. Moll. of Chalk of England, pl. 20. 
This species is from the Gray Chalk (Cenomanian) of England and 
has been referred to as similar to essendense. It is a more compressed form 
than either Acompsoceras bochumense or essendense, but has a nascent keel 
and two rows of large tubercles, one on the ventral edge and the other on 
the umbilical shoulders which are similar. The tubercles are connected by 
broad fold-like costee with intermediate shorter costations that sometimes 
bifurcate from the longer ones. 
The sutures have a large, deep, and rather narrow ventral lobe divided 
by an entire siphonal saddle. The first lateral saddle has three large 
marginals, the first lateral lobe is long, rather narrow, and bifid. There are 
but three lateral saddles, the innermost of good size and bifid. If this 
suture is correctly drawn by Sharpe, it is more like that of Barroisiceras as 
figured by Grossouvre than that of Acompsoceras. But until the young is 
known, the generic name should be considered uncertain. The sutures also 
are not unlike those of some species of the keeled and tuberculated forms 
like coupei, ete 
