ON THE PERSISTENT TYPES OF ANIMAL LIFE gI 
The accepted doctrines of paleontology are by no means in 
harmony with these tendencies of physical geology. It is generally 
believed that there is a vast contrast between the ancient and the 
modern organic worlds—it is incessantly assumed that we are ac- 
quainted with the beginning of life, and with the primal manifestation 
of each of its typical forms: nor does the fact that the discoveries of 
every year oblige the holders of these views to change their ground, 
appear sensibly to affect the tenacity of their adhesion. 
Without at all denying the considerable positive differences which 
really exist between the ancient and the modern forms of life, and 
leaving the negative ones to be met by the other lines of argument, 
an impartial examination of the facts revealed by paleontology seems 
to show that these differences and contrasts have been greatly 
exaggerated. 
Thus, of some two hundred known orders of plants, not one is 
exclusively fossil. Among animals, there is not a single totally 
extinct class; and of the orders, at the outside not more than seven 
per cent. are unrepresented in the existing creation. 
Again, certain well marked forms of living beings have existed 
through enormous epochs, surviving not only the changes of physical 
conditions, but persisting comparatively unaltered, while other forms 
of life have appeared and disappeared. Such forms may be termed 
“persistent types” of life; and examples of them are abundant 
enough in both the animal and the vegetable worlds. 
Among plants, for instance, ferns, club mosses, and Conzfere, some 
of them apparently generically identical with those now living, are 
met with as far back as the Carboniferous epoch; the cone of the 
oolitic Araucarta is hardly distinguishable from that of existing 
species ; a species of Pzzus has been discovered in the Purbecks, and 
a walnut (/weglais) in the cretaceous rocks All these are types of 
vegetable structure, abounding at the present day ; and surely it is a 
most remarkable fact to find them persisting with so little change 
through such vast epochs. 
Every subkingdom of animals yields instances of the same kind. 
The Globigerina of the Atlantic soundings is identical with the 
cretaceous species of the same genus; and the casts of lower Silurian 
Foraminifera, recently described by Ehrenberg, assure us of the very 
close resemblance between the oldest and the newest forms of many 
of the Protozoa. 
Among the Coelenterata, the tabulate corals of the Silurian epoch 
1 I state these facts on the authority of my friend Dr. Hooker. 
