MOLLUSCA — CEPHALOPODA. 
175 
In the Lower Lias of Dorset are still found very large 
])hragraocones, but other specimens show the Belemnite type 
fully” ileveloped, with pro-ostracum, ink-bag, and hooked arms. 
Of Bclemnites clongatus there is the fine specimen described 
by Huxley in the Alonographs of the Geological Survey and 
Sowerby’s original specimen from Crick tunnel near Daventry. 
The Middle Lias of Charmouth has yielded the slender 
Xiphotcutliis elongata, also described by Huxley. From the 
Upper Lias of Alderton, Gloucestershire, comes a well- 
preserved pro-ostracum. A monster phragmocone of the 
Bajocian species Bclemnites gigantcus comes from Germany. 
The Oxfordian of Trowbridge and Christian Malford in 
Wiltshii-e furnishes a large series of B. Oioenii. 
Among Cretaceous belemites, Buvalia dilatata is remark- 
able for its guard, swollen in one direction and flattened in 
the other. Actinocamax is the usual form from Cenomanian 
to Senonian, being joined by the similar Belemnitella in the 
latter Age. 
The belemnites did not die out at the close of the 
Cretaceous Epoch, but they changed in character. Styraco- 
tcuthis orientalis from the Eocene of Syria is still of the older 
type, but in most the guard was reduced in length, thickness, 
and calcification. Vasseuria from French Eocene rocks has 
such a slender yet relatively short guard. In Bcluplcm and 
Belopteriva the guard is short and somewhat swollen at its 
end, which makes a slight angle with the phragmocone ; in 
the former it expands at the sides into two wings. The 
latter genus is not far removed from the Miocene Spiruliroslra, 
already described (Fig. 85 h). In a later genus Spiridirostrina 
(not exhibited) the guard is more reduced, and in the modern 
Spinda it has disappeared (Fig. 85 c). 
Another line of evolution leads, as previously explained, 
from Beloptem to Beluscpia (Fig. 85 d) of which many 
specimens from the London Clay and Bracklesham Beds, 
are shown. Sepia itself is exhiluted from later Tertiary 
rocks (Fig. 85 e). 
Of those sheathed forms in which the calcification of the 
shell underwent a gradual reduction, the earliest known is 
Phragmoteidhis from the Upper Trias. The next in age is 
Geotevthis, of which large specimens from the Lower Lias of 
1 )orset are exhibited. These and the smaller specimens from 
the Upper Lias of Wurtemberg and Normandy show an 
expanded pro-ostracum, divided lengthwise into three areas, 
and with no trace of a phragmocone. Many of these 
Gallery 
VII. 
Wall-case 
8 . 
Table-case 
16 . 
Table-ease 
16 . 
Wall-case 
7 . 
Wall-case 
7 . 
