of the Ventriculidae of the Chalk. 45 



applied to the whole family and to the first genus is the only 

 apparent exception to this rule*. The name Ventriculites would 

 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 be 

 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 

 VentricuHdce 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 simplepoitch 

 form which is implied in the name VentricuHdce as above ex- 



Names in Morris's Catalogue. In the following classification. 



Ventriculites infundibuliformis Ventriculites cavatus or bicompli- 



catus. 



quadrangularis Brachiolites angularis. 



quadratus ? not a Ventriculid. 



radiatus Ventriculites radiatus. 



Ocellaria inclusa quincuncialis. 



nuda Ibid. 



Spongites Townsendi Ventriculites simplex. 



labyrinthica Brachiolites convolutus. 



Scyphia Fittoni Fragment of Brachiolites digitatus. 



* 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. MantelPs specific name radiatus. 



f Thus Cicero : " £x ea [anima] pars concipitur cordis parte quadam, 

 quam ventriculum cordis appellant, cui similis alter adjunctus est in quem 

 sanguis a jecore per venam illam cavam influit." — De Nat. Deor. ii. § 55. 



