REPOET 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 iu 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 Paleozoic 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 Palaeozoic 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 

 Pateocrinoids. A similar band, 10 to 20 centimetres thick, which was discovered by 

 M. Eudes-Deslongschamps in the Great Oolite at SoUers 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 Extracrinus 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 Pentacriuidos which occur associated in slabs much 

 like those formed by Extracrinus hriareus, 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 oi 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 Apiocrinidse, the abundance of Apiocrinus parhinsoni 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 aU. The coral bed at Nattheim is famous for the 

 number of Coina^wZa-remains which it contains ; though as these, like the Eiigeniacrmus- 

 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, SoUers, 

 or Sennecey-le-Grand. 



The different modes of attachment which occur among the Crinoids have been 

 discussed in Chapter II. In all the Bourgueticrinidas there is 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 Bourgueticrinidae. But the 



1 Etudes sur les etages jurassiques inferieurs de la Nonnandie, Paris, 1864, pp. 229, 235. 



2 See de Loriol, Notice sur le Pentacrinus de Sennecey-le-Grand, op. cit., pp. 11-13. 



