40 GUIDE TO THE FOSSIL INVERTEBRATE ANIMALS. 
Gallery X. 
Table-case 
13 . 
Table-cases 
13 , 14 . 
W all-case 
8 . 
Table-case 
14 . 
Table-case 
13 . 
posed of detached spicules of TetractinelHda itnd Lilhistida. 
A few larger fragments of the latter group from Sevenoaks 
are the only representatives of the com])lete skeleton. From 
the Gault there are only some specimens of Jerea and a tine 
e.Kamide of the He.Kactinellid genus Craticidaria in pyrites. 
The Upper Greensand and tlie Chalk Marl, on the other 
hand, contain great numbers, which preserve tlieir original 
form and structure. Those from the Greensand of War- 
minster, Wilts, first studied by Miss Etheldred Uenett of 
Fig. 16.— Lithisfcid sponges from the Upper Greensand of Warminster. 
a, HallirJioa costata (specimen 48174); 6, Dorijdcrma dichotamum 
(specimen P 1:260) ; c, Siphonia tulipa ; a section tlirough the upper- 
part of the sponge, showing the cloaca in the middle near the top, the 
large excurrent canals which open into it, and the fine incurrent 
canals leading from the outside to these latter (specimen P 1366). 
(t and h are reduced to ^ nat. size, and c to 4. (.A.fter Hinde. See 
Table-case 13.) 
that place (1831), are .shown in great (piantity. Among the 
Calcispongiae are good specimens ot Pharetrosponf/ici Strahcini 
from Cambridge. The folded walls of Plocoscyphia, arc 
conspicuous among the Flexactinellida, but the Lithistid 
Tetractinellida are the most richly represented. Among 
these last, particular attention may be directed to the 
peculiar lobatc forms of the Lithistid HaUirlioa (Fig. 16 a) 
with long stems, the perfect Sijjhoniuc from Blackdown 
(Fig. 16 c), the large goblet forms of Pachijpotcrion, and 
