293 
of the Ventriculidae of the Chalk. 
parison of several of these apparently anomalous fossils led me 
however to conceive that the connected rounded bodies seen in 
the former set of specimens had some relation to the very pe- 
culiarly complicated and almost angularly raised surfaces seen in 
the latter. With this clue I cut down some of these rounded 
bodies, and found the identical surfaces last named below them. 
Several sections being made, and the whole series being then 
compared, order and method became at once apparent where all 
had previously been anomaly and confusion. The characteristic 
Ventriculitic structure was detected : the Ventriculitic fold was 
traced : and the Ventriculitic root was found. 
I conceive the habit of the animal to have been very different 
in one respect from that of all the species which have hitherto 
engaged attention. While the latter stood rising upwards from 
a central root, this species, attached at one end by a root, and thus 
secured in its position, floated horizontally, like a ship riding at 
anchor. It had therefore no central cavity in the direction of its 
length, but, instead of this, it was covered by a head investing 
the upper and lateral surfaces of that whole length ; and which 
head, with rare exceptions, for such exceptions do exist, was con- 
stricted at intervals, causing the animal, when seen from above 
and entire, as in the greater part of fig. 1. PI. XV., to appear 
like several distinct globose bodies linked together. The fact 
of the head being occasionally, though rarely, not constricted at 
all, will satisfy any philosophic inquirer that such an appearance 
is deceptive, and that the explanation thus given of that appear- 
ance is the true one. Besides this, however, if the head be re- 
moved, and the lower surface of the fossil only seen, all trace of 
separation and distinctness is gone. The membrane of the wall 
does not divide into lobes, as in Brachiolites : there is simply, in 
order to ensure the greater security of the whole polypiferous 
surface, an occasional constriction of the head and narrowing of 
the plaits attached to it ; which plaits expand again, like an open 
fan, in the following compartment. 
The appearance of the plaits themselves is very remarkable. 
Their frequent constrictions give them a puckered or zigzag ap- 
pearance, so that a vertical section 
has a figure of this kind. This 
figure shows, also, how the pro- 
jecting points of the plaits are 
often attached, for security, to 
the head. When the body is broken away the cast left is very 
curious, the matrix being always broken off in many of the places 
where it has filled a pucker in the upper plait, depressed where 
there was a pucker in the lower plait. This is seen on the right 
hand of fig. 1. PI. XV. 
Fig. L. 
