1854.] OF THE ROYAL INSTITUTION. 429 
understood. Hence have arisen the hypothesis of an evolution of all 
organized types, during the course of time, from one rudimentary 
prototype; that of the succession of distinctly originating forms of 
animals and vegetables in order of the progression within their re- 
spective series ; of the coeval starting of the great groups wholly or 
mostly at the beginning, but in each instance by the lower forms of 
the type; of the representation by the faunas and floras of geo- 
logical epochs, of the successive zones of life belting the geographical 
regions between the poles and the equator ; of an uniformity of life 
arrangements throughout time and repetition through substitution of 
equal and similar groups; and of manifestations in the distribution 
of life in time of analogies that are essentially theological. 
For several years I have been persuaded that the simple and un- 
questionable phenomena of substitution of groups by representative 
groups, manifested in the arrangements of the faunas and floras of 
all geological epochs, and comparable with like phenomena exhibited 
by the geographical distribution of existing organized beings, would 
prove sufficient for the explanation of all the appearances, that have 
suggested such speculations, some purely hypothetical, some fairly 
theoretical, as those I have just indicated. The apparent contradic- 
tions and unexplained peculiarities presented by the more ancient 
epochs as contrasted with the middle and newer ones, seemed to 
depend on the incomplete state of our knowledge, and to be possibly 
explainable by supposing, that of some great geological epochs in time 
we had as yet discovered no traces. Thus the great gap between 
the Palzozoic and Mesozoic life might depend upon our not yet 
having discovered traces of the rudimentary formations that had 
been deposited during the interval between the Permian and Triassic 
epochs. 
But the rapid accumulation of paleontological facts gathered within 
the last very few years, and the great additions that have been re- 
cently made towards our knowledge of the Paleozoic fauna, all 
mainly in accordance with facts known before, have satisfied me that 
the explanation offered above does not sufficiently meet the full 
truth, and that the various theories concerning progression, develop- 
ment, &c. have all originated in the obscure perception and imperfect 
interpretation of the workings of some great law in the distribu- 
tion of organic beings in time. 
It is no longer possible, in the face of paleontological evidence, to 
hold any of the notions cited. The scale of the first appearance of 
groups of beings of any degree is most clearly not one of organic 
progression. Suitable conditions have been met by the creation of 
suitable types; no type, whether generic and therefore ideally mani- 
fested, or specific and therefore manifested actually and through 
individuals, visibly, being found to be ever repeated in time, when 
the full history of either is made out. This is a great law anda 
grand result of geological research. Nevertheless in the relative 
arrangements, so to speak, of generic types in time, there is an indi- 
