49 



even detected, necessarily stains the matrix beyond the structure 

 itself; and it requires the nicest and most painful discrimination 

 to determine what is due to structure and what to mere iron 

 stain. Feeling however that such a course of investigation could 

 furnish the" only true materials of a natural classification,, I have 

 endeavoured to overcome these difficulties. And it may save the 

 task both of making and answering many objections if I now 

 state that I have, with this object, dissected with elaborate care 

 numberless specimens, in addition to many hundreds of sections 

 of specimens both in flint and chalk, which, with the like purpose, 

 I have made. There is not one species which I have established 

 which I have not determined from actual and personal section 

 of specimens either in chalk or flint, usually both, and in which, 

 with scarcely an exception, I have not followed and traced out 

 the actual fold with the knife and needle. 



My aim has been to present such a classification and no- 

 menclature as should be intelligible and at the same time ex- 

 pressive; which, whether respect be had to genus, section, or 

 species, should give some accurate and specific idea of the point 

 on which the respective division has been founded ; that thus a 

 mere inspection of the table of classification may carry with it 

 some real and true ideas as to the objects included*. The name 



descriptions so long before the world, and so often repeated, are funda- 

 mentally erroneous, the conclusions as to the oeconomy of the animal being 

 necessarily, therefore, as fundamentally erroneous. It is upon the same 

 laborious care which has enabled me to demonstrate these facts, that I rely 

 in attempting the descriptions now to be given of the different modes of 

 folding assumed by that membrane, and the superficial appearances of 

 which have misled these observers. 



* It is usually unadvisable to alter names once applied ; but where the 

 character of an object has been wholly misunderstood, not even its generic 

 or structural character having been known (see the last note), there can 

 be no claim to retain old names. Their retention is then generally mis- 

 chievous as a mere perpetuation of error. I fully agree with Dr. Farre (ut 

 ante, p. 405, note) that oftentimes " confusion and doubt (in nomenclature) 

 can only be dispelled by beginning de novo," and so applying new names 

 in harmony with a system founded in nature and upon some definite prin- 

 ciple. I think it better to give here all the names which occur in Mr. 

 Morris's Catalogue whose objects appear to belong to the Ventriculidse, 

 a list which will, moreover, show the " confusion and doubt " which have 

 hitherto prevailed in the nomenclature of this family. 



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



Choanites flexuosus Ventriculites latiplicatus. 



Choanites subrotundus Cephalites constrictus. 



Ventriculites alcyonides [OcellariaJ Ventriculites quincuncialis. 



alternans Probably V. bicomplicatus. 



Bennettise One of the Cephalites annulati, but 



no accurate description ; and the 

 figures of Michelin and Manteil 



(V. infundibuliformis) totally differ. (V. cavatus) 



D 



