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 palaeontologists 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 palaeozoic 

 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 palaeontological 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 



