40 
CORALLINE CRAG. 
forms, belonging to southern genera; the third, Cryptangia Woodii^ 
is a branching form always encrusted with Cellepora. The 
Flabellum is rare, the others are fairly abundant. 
The Echinodermata amount to about 16 species, only three of 
which 
are 
living. 
still 
Fig. 6. 
Temnechimts excavatus, 
S. V^'ood. 
Natural size. 
point to warm seas, but 
The genera 
nothing more definite can be said about 
them. Ternnechinus excavatus (Fig. 6), 
Amphidetus (spines), and a species of 
Brissus are common; all the others are 
rare. This class is also represented in 
the Coralline Crag by three species of 
Comatula. 
The Hydrozoa are peculiar and abun¬ 
dant, though only belonging to two 
species of Hydractinia. H. circumves- 
tiens will be constantly met with, and is 
very likely to be mistaken for a Cellepora. 
It overgrows spiral univalves, genei’ally 
Trophon alveolatus (see Fig. 7). Cellepora edax^ on the other 
hand, usually incrusts small shells. Fig. 7. 
especially Natica and Turritella. It Hydractinia circumvestiens, 
gradually eats away the shell, so that S. Wood, 
in most specimens the walls have Natural size, 
entirely disappeared, and what is 
found is a mass of Cellepora, with a 
spiral cavity retaining the impress of 
the external shape of its host. 
Of Cirripedes, Darwin described 10 
species, 4 of them extinct. The most 
conspicuous is the Balanus tintinabu- 
lum, a large species of barnacle, which 
often occurs in clusters of consider¬ 
able size. It and the other living 
forms belong principally to warmer 
seas than ours. The rest of the Crus¬ 
tacea call for little remark. Prof. 
T. R. Jones records 19 species of 
Entomostraca, mostly belonging to the genus Cythere, and all 
except one are extinct. Few of the higher Crustacea of the 
period are known, but Prof. Prestwich mentions six species 
determined by Dr. H. Woodward ; they are living forms. 
Scattered bones and teeth of fish are often met with, the most 
abundant remains being gadoid otoliths. Teeth or dermal spines 
of the Skate and Wolf Fish occur, and the broken state in which 
so many of the mollusca are found, is probably largely due to the 
presence of these shell-eating fish. An extinct species of Tunny 
( Thynnus scaldiensis') has also been found. 
Only one Bird has yet been recorded, but this is the ocean- 
loving albatross. Contemporaneous Mammals are represented by 
one of the larger Dolphins, for though land species occur in the 
nodule bed, none have yet been found higher up, away from the 
