Badiata. 23 



those of M. Tiedemann and many modern authors on their 

 anatomy, have enabled us, of late years, to acquire a more 

 complete acquaintance with these animals, than with those 

 of any other division of the department of radiata, with the 

 single exception of living polypes. Accordingly, the relations 

 of the living and fossil types of the class of Echinoderms 

 now appear in the most evident manner. The Crinoides are 

 the prototype of the whole class. Not only does geology 

 shew this, but also what we know of the first states of some 

 species of this family {Comatula and Fentacrinus Europwus) 

 equally confirms it. We may even say that the Crinoides 

 present us with a kind of synthesis of all the families of this 

 class, by the different forms they assume ; for example, in the 

 Cystides which remind us of theEchinidse.or in theMelocrines, 

 which make a near approach to the Asterise. It is only the 

 Holothurise which seem to be exclusively confined to the pre- 

 sent creation, and this family is precisely that which occupies 

 the highest rank among the Echinoderms; while the Crinoides 

 which occur at the lower part of this series, would appear to 

 be the first ; then come the Asterise, already numerous in the 

 triassic formations; and, finally, the Echinidae, whose greater 

 development characterises the Jurassic, cretaceous, and ter- 

 tiary formations. But each of these formations has its par- 

 ticular forms, and even its own genera ; the Crinoides of 

 the palaeozoic formations are not the same as those of the se- 

 condary formations, and they disappear almost entirely in 

 the cretaceous and tertiary deposits, being no longer repre- 

 sented in the actual epoch, but by a few fixed species, and 

 by Comatulae, which go back, it is true, as far as the Jurassic 

 formations, but which approximate, in many respects, to true 

 Asteriae. The latter, in their turn, are represented in many 

 formations by particular genera, which are still imperfectly 

 known, with the exception of some types belonging to the 

 chalk, of which well preserved specimens have been found in 

 England. Lastly, the Echinidae, so abundant in the superior 

 secondary and in the tertiary formations, here everywhere 

 appear under new forms ; so that the genera of the existing 

 creation do not go back, for the most part, beyond the ter- 

 tiary formations, with the exception of the Cidaris, spe- 



