KNEMICERATID&®. 145 
Engonoceratide. It has been therefore assumed that they had a similar 
stage in which the venter was concave and had continuous ridges on the 
ventro-lateral angles. 
KNEMICERAS Bohm.‘ 
There are but two lines of nodes on the sides and straight broad costee, 
bifurcating between them. The venter is broad and concave, the cost 
and nodes are opposite, and the venter is often transversely ridged between 
the nodes. The ventral lobes have the same shape as in Buchiceras and 
Roemeroceras and have similar truncated siphonal saddles. ‘The ornamenta- 
tion and form resemble these genera, but there is no keel at any age and 
the development is quite distinct. The young are not compressed as in 
Buchiceras, and the ventral zone is concave in an early neanic substage and 
remains concave throughout life. This shows similarity to Engonoceras and 
Placenticeras. The lateral lobes and saddles are similar to those of Engono- 
ceras, but the inner laterals are fewer in number and the first lateral saddles 
are more complicated. The divisions of the first may be counted as four 
or even five lateral saddles derived from a primitive first lateral. Until 
some one ontogeny is studied the correct enumeration can not be given. 
The young were seen in section. The rounded venter of the nepionie 
stage is succeeded in the neanic stage by a flat-ventered volution with quad- 
ragonal outline, and the concave venter appears in the earliest part of the 
ephebic stage. At this time the venter is very broad, the sides flat and 
obviously costated and tuberculated on the umbilical shoulders. Whether 
there were tubercles on the edges of the venter was not determinable. 
At an early neanic substage the umbilicus was open, the venter flat 
and broad, but narrower than the dorsal diameter through the umbilical 
shoulders, the lateral zones flat and convergent, the umbilical zones well 
developed. These characters and the broad costz and nodes of the later 
stages and the venter are similar to those of Pulchelliidee, but the division 
of the first lateral saddles in full-grown specimens and other sutural 
characters are dissimilar. The species discovered in the Cenomanian of 
Portugal appears to indicate that the real age of the fossils found at Mount 
_ Lebanon is Cenomanian, although, as may be seen by the context, I have 
doubts whether any of the latter belong to the fauna of the rocks in which 
they have been found. 
« Zeitschr. Deutsch. geol. Gesell., Vol. L, 1898, p. 200. 
MON XLIV—03 10 
