180 
DR. MANTELL ON BELEMNITES, ETC. 
Fig-. I“, Part of fig. 1, slightly magnified to show the striated surface ; a. marks a 
denuded space, exposing the internal layer. 
Fig. 11. Shows the perfect form of the peristome, a ; though much compressed, the 
cavity of the chamber, partially filled with clay, is well-defined. 
Fig. III. This specimen is also perfect, but in consequence of its position in the clay, 
only one-half of the basal or upper part of the margin of the peristome (a) 
is visible. 
Fig. IV. Ammonites Jasoni, from Trowbridge, with two elongated processes extending 
from the margin of the aperture, bearing some analogy to the shelly pro- 
longations from the peristome of the Belemnite, Plate XV. fig. 3, b, b'. 
Fig. V. A phragmocone showing the ventral (?) aspect of the chambered apex, with 
two parallel longitudinal bands extending upwards (b). 
PLATE XIV. 
Fig. I. A restored outline of the animal of the Belemnoteuthis, so far as at present 
known. 
a. The cephalic arms. 
b. Remains of a pair of long tentacula. 
c. The eyes. 
d. The pallial fins. 
e. Ink-bag. 
f. f. The mantle. 
g. The phragmocone ; the letter indicates the visceral chamber of the same. 
i. Apical or distal part of the phragmocone. 
k. Two longitudinal bands on the ventral aspect of the same. 
Fig. II. Outline of the known parts of the Belemnite. 
a. a. The capsule or periostricum. 
a', a'. The horny expansion of the same forming the receptacle which sur- 
rounds the basal chamber and peristome of the phragmocone. 
b. The guard or osselet, one-half being removed to show the radiated struc- 
ture, and the alveolus with the apical part of the phragmocone, at c. 
c. The chambered distal extremity of the phragmocone. 
d. The visceral chamber of the same. 
e. e. Two calcareous processes arising from the margin of the peristome at 
/./• 
Fig. III. Phragmocone of Belemnoteuthis. 
a. The visceral chamber. 
b. Ridge on the dorsal side of the apex. 
Fig. IV. A phragmocone of Belemnoteuthis seen on the ventral aspect. 
b. Two nearly parallel elevated longitudinal bands. 
