REPORT ON THE CRINOIDEA. 131 
It is well known that the Crinoids were equally plentiful in several former geological 
periods. In the British area, for example, there are the remains of enormous forests of 
Crinoids both in the Silurian and in the Carboniferous rocks. The marvellous abundance 
of these animals in beds of the same age in America is well known. In a less degree also 
the Silurian of Sweden, the Devonian of the Eifel, and the Carboniferous of Belgium and 
Russia were characterised by a great development of Crinoid life. This terminated, 
however, with the close of the Palzeozoic epoch ; but in the Lower and Middle Lias, both 
of Britain and of the Continent, there were enormous colonies of Extracrinus, slabs of 
which are so well known in every museum. Although the limestone bands which are 
made up of the fragments of the skeleton of Extracrinus are by no means so thick as 
the Paleozoic Crinoidal limestones, yet the association in one place of a large number of 
individuals must have been, for the time at least, as considerable as in the case of the 
Paleocrinoids. A similar band, 10 to 20 centimetres thick, which was discovered by 
M. Eudes-Deslongschamps in the Great Oolite at Soliers near Caen,’ is evidence of a 
singularly localised colony or “Station” of Pentacrinus (Extracrinus?). For no trace 
of a similar bed occurs in other sections of the Great Oolite in the neighbourhood. - 
Another horizon at the top of the Great Oolite, near Sennecey-le-Grand,’ is marked by 
the very great abundance of a species of Hxtracrinus which is also found in corresponding 
beds elsewhere (in the Department de la Meurthe) ; while the Forest Marble of Gloucester- 
shire contains numerous remains of Pentacrinidze which occur associated in slabs much 
like those formed by Eatracrinus briareus, though somewhat less extensive. 
Although the Middle and Upper Jurassic rocks of this country and of the Continent 
have been found to contain numerous species of Pentacrinus, I do not know that any large 
forests of them have been met with, like those of the Lias, Great Oolite, and the Recent 
Seas; and the same may be said of the Cretaceous and Tertiary beds. 
As regards the Apiocrinide, the abundance of Apiocrinus parkinsoni in the Bradford 
clay is well known, and the Sequanien (Coral Rag) of the Continent is exceedingly rich 
in Millericrinus. The same is true of Eugeniacrinus in the White Jura of Wurtemberg, 
though it does not occur in Britain at all. The coral bed at Nattheim is famous for the 
number of Comatula-remains which it contains ; though as these, like the Eugenacrinus- 
calyces, are all more or less rolled and fragmentary, we do not meet with evidence of 
gregarious habits such as is represented by either of the colonies of Lyme Regis, Soliers, 
or Sennecey-le-Grand. 
The different modes of attachment which occur among the Crinoids have been 
discussed in Chapter II. In all the Bourgueticrinide there 1s a spreading root of variable 
extent, the subdivisions of which attach themselves by calcareous expansions to foreign 
bodies. Holopus is a permanently fixed type like the Bourgueticrinide. But the 
1 Btudes sur les étages jurassiques inférieurs de la Normandie, Paris, 1864, pp. 229, 239, 
2 See de Loriol, Notice sur le Pentacrinus de Sennecey-le-Grand, op. cit., pp- 11-18. 
