Appendix to Chapter V. 431 
family of sessile cirripedes, has been discovered by Mr. Woodward 
in the upper chalk; so that we now have abundant evidence of 
the existence of this group of animals during the secondary 
period. 
The case most frequently insisted on by palzeontologists of the 
apparently sudden appearance of a whole group of species, is that 
of the teleostean fishes, low down, according to Agassiz, in the 
Chalk period. This group includes the large majority of existing 
species. But certain Jurassic and Triassic forms are now 
commonly admitted to be teleostean; and even some palzozoic 
forms have been thus classed by one high authority. If the 
teleosteans had really appeared suddenly in the northern 
hemisphere, the fact would have been highly remarkable ; but 
it would not have formed an insuperable difficulty, unless_ 
it could likewise have been shown that at the same period 
the species were suddenly and simultaneously developed in 
other quarters of the world. It is almost superfluous to re- 
mark that hardly any fossil fish are known from south of 
the equator; and by running through Pictet’s Palaeontology it 
will be seen that very few species are known from several 
formations in Europe. Some few families of fish now have 
a confined range ; the teleostean fish might formerly have had 
a similarly confined range, and after having been largely 
developed in some one sea, might have spread widely. Nor 
have we any right to suppose that the seas of the world have 
always been so freely open from south to north as they are 
at present. Even at this day, if the Malay Archipelago were 
converted into land, the tropical parts of the Indian Ocean 
would form a large and perfectly enclosed basin, in which any 
great group of marine animals might be multiplied; and here 
they would remain confined, until some of the species became 
adapted to a cooler climate, and were enabled to double the 
southern capes of Africa or Australia, and thus reach other and 
distant seas. 
From these considerations, from our ignorance of the geology 
of other countries beyond the confines of Europe and the United 
States; and from the revolution in our paleontological knowledge 
effected by the discoveries of the last dozen years, it seems to 
me to be about as rash to dogmatize on the succession of organic 
