108 GENESIS OF THE ARIETIDA. 
Angulatus zones contain principally radical species and their immediate deriva- 
tives. The Bucklandi zone is characterized, with some exceptions occurring only 
in the Upper Bucklandi bed, by the presence of truly progressive forms. The 
highest beds, the Obtusus and Oxynotus zones, are almost exclusively the homes 
of more or less degenerate and geratologous forms. 
Extraordinary and unforeseen correlations, such as these, between chrono- 
logical distribution and a biological classification founded upon the life history of 
the individual, cannot be accidental. We have already shown, in preceding chap- 
ters, that our classification of series is natural, and capable of verification by means 
of the cycles which are found to be present in the history of the individual and of 
the group. The process of verification does not, however, end with this, since 
approximately exact agreements may be found between the paleozodlogical and 
geological records wherever both classes of facts exist and have been minutely 
studied. 
There is even some evidence that cycles may be traced in the so-called con- 
temporaneous faunas of the same horizon. Thus, what we have said about the 
analdainic faunas of England and the basin of the Rhone indicates this possibility. 
These faunas show an extraordinary evolution of the geratologous forms of the 
geratologous series; the aldainic basins show, on the contrary, in so far as the 
Cote d’Or and South Germany are concerned, an extraordinary assemblage of 
the progressive forms of the Arietidw, whereas the originating or aldainic centre 
of the family in the Northeastern Alps has a fauna in which the radical series 
are enormously developed. Zs would seem almost evidence enough that there are 
cycles in the chorological migration, as well as in the chronological evolution of forms. The 
whole might be represented as a complex of vortices, in which the result is apt to 
be a cycle, whether the spiral lines of evolution form small vortices upon the same 
or nearly the same horizons, or whether the picture is the blending of all these 
into one great spiral, or a series of more or less parallel and blended spirals 
ascending through geologic time. 
Fauna oF THE PROVINCE OF THE MEDITERRANEAN. — TaBLeE VI. 
It was intended to omit this table, as well as those of the North German 
basin, Italy, Corsica, Spain, ete., the species of which have not yet been fully 
described and illustrated, since it is not practicable in such researches to accom- 
plish much unless aided by very full information. Lists of names from which 
these faunas might have been made up are rarely of much use, since authors 
differ essentially in the identification of species, and therefore we have not 
considered it safe to venture upon tabulating them. The publication of Wihner’s 
and Neumayr’s researches, however, induced the author to attempt to give a 
tabular view of the Mediterranean province. It has not been found practicable 
to carry out the system of connecting the forms by lines representing genetic 
bonds, except in so far as they have been published by the authors named above, 
and the usual connecting lines have therefore been omitted in series occurring 
above the Lower Bucklandi bed, and in all the genera of the Levis Stock. 
