45 
of the Ventriciilidse of the Chalk, 
applied to the whole family and to the first genus is the only 
apparent exception to this rule*. The name Ventriculites ^ov\di 
certainly not have been applied to any of these bodies, or to the 
family, by myself. It was applied by Dr. Mantell to the few 
forms found by him, under the idea of the internal cavity being 
the true digestive surface of a single animal. Though the idea 
under which the name was thus applied has been shown to he 
wholly erroneous, I have been unwilling, out of respect to the 
many labours of Dr. Mantell in the field of palaeontology, to 
reject, as others have done without assigning any reason, this 
generic appellation ; and I have justified myself in its retention 
by the classical use of the same word, though in a secondary 
sense only, in a very different way, viz. as applied to mere sacci- 
form cavities f. It will be understood, therefore, that the terms 
Ventriculidce and Ventriculites bear no reference to any digestive 
cavity, but simply to the fact of the creatures to which they are 
applied always assuming forms which display a central cavity 
more or less simple. I am glad that this modification in the 
meaning of the word enables me to retain a name which will 
always bring to the inquirer^s recollection the long and successful 
labours of Dr. Mantell. 
It is impossible to examine an extensive series of remains ex- 
hibiting the characteristic structure of the Ventriculidse, without 
perceiving that, however widely in other respects the individuals 
differ from one another in the mode of fold of their membrane, 
they all range themselves within one or the other of three strongly 
marked and constant modifications, quite independent of mere 
size. 
The first in natural order, as having most of that simple 
form which is implied in the name Ventriculidm as above ex- 
Names in Morris's Catalogue. 
V entriculites infundibuliformis 
quadrangularis 
quadratus 
radiatus 
Ocellaria inclusa 
nuda 
Spongites Townsendi 
labyrinthica 
Scyphia Fittoni 
* The termination ites ” is not in itself very classical, but has been so 
generally employed as to be a convenient and intelligible distinctive mark 
of fossil generic appellation. Hence I retain it in '' Ventriculites,” and am 
therefore obliged so to terminate the other generic names. I am glad to be 
able to retain, consistently. Dr. MantelFs specific name radiatus, 
f Thus Cicero : £x ea [anima] pars concipitur cordis parte quadam, 
quam ventriculum cordis appellant, cui similis alter adjunctus est in quern 
sanguis a jecore per venam illam cavam influit.” — De Nat. Deor, ii. § 55. 
In the following classification. 
Ventriculites cavatus or bicompli- 
catus. 
Brachiolites angularis. 
? not a Ventriculid. 
Ventriculites radiatus. 
quincunciaiis. 
Ibid. 
Ventriculites simplex. 
Brachiolites convolutus. 
Fragment of Brachiolites digitatus. 
