355 
of the Ventriculidse of the Chalk. 
latus, as to observations u]3on the proeesses, applies equally to 
every species of the present genus. Enough^ however^ can be 
detected to determine the fact of their presence. 
This species must, in its recent state, have been singularly 
striking. It is difficult, indeed, to conceive anything more beau- 
tiful than must have been its exterior with each of its regularly 
ranged lobes covered with its myriads of living polyps and their 
ever-active tentacles. 
All my specimens are from the Upper Chalk. 
2. Brachiolites elegans. PI. XV. fig. 4. 
Membrane simple and without any primary fold : brachial fold 
beginning almost at the acute base, and rapidly increasing in 
broad and swelling lobes closely arranged round a central ca- 
vity, and terminating in a simple and regular crown, open at 
the top, and wdiich, rising from the midst, reaches to a consi- 
derable distance above the highest lobes, and is of about half 
the diameter of the whole body. 
This form is, in its fossil state, frequently so beautiful that I 
have hence chosen its specific name. The effect is heightened 
by the fact that the root of this species is usually long, and often 
maintains the' same diameter for a height of nearly two inches. 
The primary membrane is exactly similar to that of Ventri- 
culites simplex : the brachial folds are deep aud broad, their inner 
surface being freely exposed to access of sea-water from the large 
internal cavity. The crown is one of the most remarkable fea- 
tures of this species. It is regular and plain ; springs from the 
lower edge of the most deeply folded lobes, and rises, unbroken, 
to a clear and even margin. A glance at fig. H, p. 291, illus- 
trative of the fold of Cephalites campanulatus, will aid in un- 
derstanding the anatomy of the present species ; broad convolu- 
tions here replacing the plaits seen in that specimen, and the 
crown being always straight-sided, and never, I believe, assuming 
a funnel form. Nothing can show more convincingly than this 
peculiar crown, that the forms of the Ventriculidse are not 
merely arbitrary massings of an amorphous or simply cumulative 
organism, or mere examples of vegetative repetition,^^ but that 
there was a type appointed to each which it should attain, and 
each having its special adaptations. In perfect specimens this 
head is never wanting, though it is rarely, if ever, to be seen 
without the aid of the knife ; whence it is that it has never, so 
far as I am awnre, been heretofore observed. 
The species appears to be characteristic of the Upper Chalk. 
’ 3. Brachiolites convolutus. PI. XV. fig. 5. 
Membrane coarse in texture, simple and without any primary 
24* ‘ 
