37 
of the Ventriculidse of the Chalk. 
the forms hitherto collected there of true Ventriculidce are very 
rare, if we may judge from the specimens in the museum of the 
Yorkshire Philosophical Institution, for the opportunity of care- 
fully inspecting which specimens I am indebted to the courtesy 
of Mr. Charlesworth*. In England these fossils have not hitherto 
been recognized in any other than the Cretaceous group. It is 
probable that careful search will reveal them throughout all the 
members of that group. At present they have been found in 
five divisions of it ; viz. the Upper Chalk, the Middle Chalk, the 
Lower Chalk, the Chalk Marl, and the Upper Greensand. The 
prevalence indeed of certain forms is characteristic of certain of 
these divisions t ; a result which unexpectedly displayed itself 
after the classification presently to be exhibited had been worked 
out from a cautious study of the individuals, and the value of 
which result must therefore strike every inquirer. The particular 
divisions characterized by the predominance of one or the other 
class of forms will be shown in severally describing those forms. 
There is no « priori reason why representatives of these forms 
should not be found in older and in newer formations than these 
cretaceous beds. Still the fact of their not having been thus found 
in England, where, in those cretaceous beds, some of them so much 
abound, leads to some hesitation in relying implicitly on the 
alleged much lower stratigraphical position of some foreign forms. 
The foreign forms from the true chalk appear to be few and rare ; 
but there are several figures in Goldfuss, to some of which I have 
already alluded J, probably representing forms belonging to this 
family, which are there given as from the “ Jurakalk.^^ In the 
* In addition to the acknowledgements which I have alread}^ made, I 
have the further pleasure of now recording the kindness, in affording me 
the means of examining different specimens from very various localities, of 
Mr. Lyell, Mr. Wetherell and Mr. Oakeshott of Highgate, Mr. Cunnington 
of Devizes, Mr. Catt of Brighton, and Mr. Whittle of St. John’s College, 
Cambridge, besides that of Mr. Charlesworth as above-mentioned. I must 
also acknowledge the kind assistance afforded me by Mr. Waterhouse of 
the British Museum, in facilitating the task of inspecting the specimens in 
that collection. To the President of the Geological Society I am also in- 
debted for the prompt courtesy with which he has enabled me to avail 
myself efficiently of illustrations from the valuable museum of that Society. 
I would take this opportunity of saying that I shall be greatly obliged 
by any illustrations and opportunities similar to those which have already 
been so kindly and liberally afforded to me. 
t See observations in the Ann. and Mag. of Nat. Hist. vol. xx. p. 337. 
An interest beyond even that which they are calculated intrinsically to ex- 
cite is thus given to these fossils, of the same nature as that which attaches 
to a series of Ammonites from different beds. 
J Ante, vol. xx. p. 78. It is proper to state that there are many forms, 
besides those thus specified, figured by Goldfuss as from the Jurakalk, and 
which I have not much doubt are Ventriculidae. I have only enumerated 
the more obvious. 
