363 
of the Ventriculidse of the Chalk. 
ropes of a tent, by whieh alone it is securely kept in a position 
which, swinging on its single central support, it could not other- 
wise sustain for an instant*. 
Such are the normal characters of this very curious and inter- 
esting species. As was to be expected in so delicate a species, 
specimens are, not unfrequently, found exhibiting abnormal forms; 
owing either to displacements of the dead mass before or during 
the process of fossilization ; or, sometimes, to incomplete deve- 
lopment of the living mass, or accidents to the living animal, — 
accidents to which, from its delicacy and remarkable fonn, it 
would be peculiarly liable. Thus I have a flint ten inches in 
length covered with irregular markings, but in which may I 
think be clearly traced displaced portions of an individual of this 
species. I have similar specimens in chalk in which it appears 
clear that the originally flat arms have been tumbled and bent 
over upon one another in confusion. I have myself collected 
more than one specimen which would seem never to have had 
more than two of the flattened arms. In such cases compensa- 
ting provisions are found ; and, there being no large central ca- 
vity, the lateral perforations are found larger than usual, and on 
both edges of what thus becomes one elongated double fold. I 
have another most interesting specimen, in which the opening of 
the central cavity is in an abnormal position, namely on one side ; 
but still it is there present in all its completeness, thus showing 
the necessity and the presence of some compensation where any 
abnormal conditions exist. There is, indeed, no species among 
the Ventriculidse which bears more conclusive evidence to the 
truth of the views heretofore expressed as to the charaeter, affi- 
nities, and habits of the recent animal than does Brachiolites an- 
gularis. 
I cannot conclude the account of this species without express- 
ing the strong feeling which its examination impresses of the 
wonderful variety, and always completeness, of the contrivances 
by which nature has effected her ever-present purpose of securing 
the well-being and permanent safety of every creature she has 
made. The theorists on mere-\ “ Vegetative Repetition ” and on 
Progressive Development will find themselves equally at fault 
in the examination of this species. There is no form which the 
naturalist can study with greater interest, admiration and in- 
struction than that of Brachiolites angularis. 
This species is found in both Upper and Middle Chalk. 
* The reader will recal the description of an abnormal form of root already 
given (p. 92). That specimen is of the genus Ventriculites. What is there 
abnormal becomes a special character in the present species. 
t This word is used advisedly, to distinguish those who thus theorize from 
those who philosophically inquire into the important questions of serial ho- 
mologies. 
