36 
shire, the age of the bed is stated to he London clay, having a 
Bracklesham facies like the London clay which occurs at 
Portsmouth. The Terebratula were found in masses, a number 
of specimens have been sent to me by Mr. Elwes. The shells 
are very thin and easily separate from the sandy clay with 
which thej^ are filled, so they require to be hardened. The 
French specimens are also very fragile. 
This species was described bj^ Valenciennes in Lamark’s 
“ Animaux sans Vertebres ” as an ovate shell, depressed, smooth, 
fragile, front margin biplicated, beak not incurved. The Catis- 
field specimens are dark coloured and appear to be larger and 
more globose than the French species, but a series of French 
specimens would be required before it could be determined 
whether it was advisable to give them a varietal name. Mr. 
Elwes has fortunately been able to expose the loop, which 
is short and simple. The shell structure shows the usual 
perforations, which are large and numerous. The rarity of 
brachiopoda in the English Tertiary beds is remarkable. It 
may be due to the want of sheltered habitations, as, according 
to Dr. Davidson, they live at depths from half tide-mark to 
2600 fathoms, and are found in tropical and polar seas, so that 
it cannot be on account of either depth of water or climate. 
Terebratula abound among the coral reefs, and in rocky places 
which are not exposed to rough tidal action. The conditions 
under which the Eocene deposits of England were formed 
would be unfavourable to the growth and preservation of 
brachiopoda, as Lyell says “No formations can be more 
dissimilar, on the whole, in mineral character, than the Eocene 
deposits of England and Paris, those of our own island being 
almost exclusively of mechanical origin ; accumulations of mud, 
sand, and pebbles : while in the neighbourhood of Paris we 
find a great succession of strata composed of limestones, 
some of them siliceous, and of crystalline gypsum, and siliceous 
sandstone, and sometimes of puie flint used for millstones.” 
Some of these conditions would be favourable for the develop¬ 
ment of brachiopoda. It may be that Catisfield was protected 
from strong tidal action during the deposition of the London 
clay, and this would account for the abundance of Terebratula 
bmnuata in that locality. 
