282 Mr. T. Austin on the Connexion between 



One or two detached pieces, it is true, appear to belong to well- 

 known European species, but till more perfect specimens are 

 obtained the identification cannot be complete. 



Dr. Troost claims to have added two hundred new forms to 

 the long catalogue of these fossils already known. After making 

 considerable allowance for the zeal of a first discoverer in bestow- 

 ing a name on every fossil new to him, by deducting a fair per- 

 centage from the gi'oss amount, a very considerable number of 

 new genera and species (probably all the latter) still remain to 

 make Dr. Troost's discoveries of great value and interest to 

 science in various ways, not the least of which is that of enabling 

 us to compare the forms inhabiting the seas of our own latitude 

 in remote epochs with those which existed three thousand miles 

 distant in the West. On making this comparison we find that 

 each portion of the globe had in those earlier periods its own 

 peculiar animals, each equally distinct and strongly marked in 

 character as at the present day. Few genera and species being 

 common to such distant localities as Europe and America, yet 

 when we take a casual view of the fossils found on the two con- 

 tinents, we are instantly impressed with the idea of their general 

 resemblance to each other ; but when we come to examine them 

 more closely, the resemblance is no longer maintained. Genera 

 that at first appear identical with long known forms, prove per- 

 fectly distinct, and species which seem to a casual observer as 

 one and the same, under the eye of the scientific inquirer are 

 found to be wholly dissimilar in the arrangement of the calcareous 

 framework. Thus the Agaricocrinus of America closely ap- 

 proaches our AmpJioracrinus, but it is in reality intermediate 

 between that genus and Actinocrinus, and so on of many others. 



Many distinguished naturalists have published detailed de- 

 scriptions of various Crinoids ; among these may be mentioned 

 M. d'Orbigny, Count Munster, and M. Romer. The researches 

 of these and other observers have greatly enlarged the limits of 

 fossil zoology by increasing our acquaintance with those ancient 

 and extinct genera and species of Crinoidese which supply many 

 important links which were before wanting to complete the chain 

 in the scale of organic life, from the period when the world was 

 first inhabited to the present time. In this manner as our in- 

 formation increases we find a perfect and unbroken succession of 

 organic beings gradually developed in accordance with the phy- 

 sical changes that have taken place on the earth ; changes so 

 manifest, that the stratified rocks may be distinguished from each 

 other not only by mechanical structure, mineral condition, che- 

 mical composition, arrangement and position, but above all by 

 their fossil contents. 



The manner in which these fossil bodies or organic remains 



