164 On the differences between Types, ^c. 



can leave no doubt in our mind that these prophetic types really fore- 

 shadowed that diversity of forms which has been created since they 

 have gone by. We may also say that these prophetic types lay be- 

 fore us the course of thoughts which has been carried out in the plan 

 of creation by the Supreme intelligence, who called them into exist- 

 ence in rich order of succession, and in so diversified relations. The 

 recognition of this prophetic character of certain types of extinct ani- 

 mals is not only important in a philosophical point of view ; I have 

 no doubt it will ultimately and rapidly lead to a better, fuller, higher, 

 and deeper understanding of the various relations which exist 

 between animals. Let rae at once point to some of these rela- 

 tions which might never have been understood but for this appre- 

 ciation. 



Among Crinoids, we have not only progressive types, as I have 

 already quoted, but we have also prophetic ones. The Cystidse are 

 truly prophetic of the Echini proper. I may only mention the genus 

 Echiuocrinus to shew the link. 



The Pentremites, again, are the prophetic type foreshadowing the 

 starfishes. And often in subordinate groups we may find such close 

 relations between genera of the same minor divisions ; such, for in- 

 stance, as the genus Encrinus, in which the genera Apiocrinus and 

 Pentacrinus, are simultaneously foreshadowed. Perhaps, in this 

 case, a distinction might be introduced between truly prophetic types 

 and synthetic types, in which the characters of later groups are 

 rather more combined than really foreshadowed. 



As for the relation between older types and the embryos of the 

 living representatives of the same families which are so extensively 

 observed in almost all groups of the animal kingdom, which have 

 existed during earlier periods, it may best be expressed if we call 

 those fossils which exemplify, in full grown animals, forms which 

 exist at present only in the earliest stages of growth of our living 

 animals, Embryonic Types, in counterdistinction from the progressive 

 types, and from the prophetic types. These embryonic types may 

 be purely such, or they may be at the same time either progressive 

 types, or even prophetic types. I shall call purely embryonic types 

 those in which we recognise peculiarities characteristic of the em- 

 bryo of the same family. For instance, the older Sauroids, which 

 liave the upper lobe of the tail prolonged, or the common Crinoids 

 provided with a stem, which resemble the young Comatulse, &c., &c. 

 I shall distinguish, as progressive embryonic types, those in which 

 we recognise simultaneously a relation to the embryo of the same 

 family, when they form besides a link in the natural chain of pro- 

 gressive development. Such, for instance, as the oldest Salamanders, 

 or the earliest Sirenoid Pachyderm. Finally, I shall call prophetic 

 embryonic types those in which we have embryonic characters, com- 

 bined with the peculiarities which stamp the type as a prophetic one, 



