CONCLUSIONS. 571 
have been an inconvenient organ in this new manner of living, all 
the individuals which had a smaller number of caudal vertebrae 
survived their congeners; consequently a form at last originated 
with a very short tail: our well known order of Pinnipeds for which 
I now propose the name of Brevicaudata. | 
All the members however, of the second section accustomed 
themselves more to the sea, and therefore all the members which 
were best adopted for this manner of living successively survived 
their less privileged congeners, and finally the sea-serpents remain- 
ed; animals which are so excellently adapted to an aquatic life 
and rapid movement, that their tendency to become extinct can 
only be explained by the singular phenomenon that colossal ani- 
mals bring forth very few young ones, only two, or only one, at 
a time, and only after very long intervals. For these animals | 
already proposed above the name of Lougicaudata. They form with 
the Brevicaudata the order of Pinnipedia. 
If this view is better, (and who will tell us this with any cer- 
tainty?) the phylogenetic table should be altered as follows: 
Auriculata. Trichecidae. 
E Gressigrada. Inauriculata. 
BS : | 
= Longicaudata. Brevicaudata. 
Long-tailed early forms Basilosaurus. 
of Pinnipedia. 
Propinnipedia, long-tailed 
ancestors of Pinnipedia 
and Basilosaurus. 
In the first table I have tried to show two things. 
Firstly: — With a horizontal dotted lme I have separated the 
still living animals or groups from those who have become extinct ; 
the former are placed above, the latter beneath the dotted line. 
And Secondly: — With the different lengths of the vertical 
dotted lines I have tried to show the different relative lengths of 
time-periods wanted by the different species or groups to be formed , 
so to speak, from that species or group which in this table is placed 
exactly beneath it, and with which it is united by a dotted line. 
It is clear that the evolution must have happened, geologically 
spoken, with extreme rapidity there, where the animals were entir- 
ely changing their manner of living, be it from a terrestrial one 
