chap, xiv.] THE NEOTROPICAL REGION. 13 



Amazon. The ancient Sirenoidei, also found in Australia and 

 Africa, have the Lepidosiren as their American representative. 

 Lastly, Ellipisurus is a genus of rays peculiar to the fresh waters 

 of South America. We may expect these numbers to be largely 

 increased and many new genera to be added, when the extensive 

 collections made by Agassiz in Brazil are described. 



Summary of Neotropical Vertebrates. — Summarizing the pre- 

 ceding facts, we find that the Neotropical region possesses no 

 less than 45 families and more than 900 genera of Vertebrata 

 which are altogether peculiar to it ; while it has representatives 

 of 168 families out of a total of 330, showing that 162 families 

 are altogether absent. It has also representatives of 131 genera 

 of Mammalia of which 103 are peculiar to it, a proportion of 4 ; 

 while of 683 genera of land-birds no less than 576 are peculiar, 

 being almost exactly f- of the whole. These numbers and pro- 

 portions are far higher than in the case of any other region. 



Insects. 



The Neotropical region is so excessively rich in insect life, it 

 so abounds in peculiar groups, in forms of exquisite beauty, 

 and in an endless profusion of species, that no adequate idea of 

 this branch of its fauna can be conveyed by the mere enumera- 

 tion of peculiar and characteristic groups, to which we are here 

 compelled to limit ourselves. Our facts and figures will, how- 

 ever, furnish data for comparison ; and will thus enable those 

 who have some knowledge of the entomology of any other 

 country, to form a better notion of the vast wealth of insect life 

 in this region, than a more general and picturesque description 

 could afford them. 



Lepidoptcra. — The Butterflies of South America surpass those 

 of all other regions in numbers, variety and beauty ; and Ave 

 find here, not only more peculiar genera and families than else- 

 where, but, what is very remarkable, a fuller representation of 

 the whole series of families. Out of the 16 families of butter- 

 flies in all parts of the world, 13 are found here, and 3 of these 

 are wholly peculiar — Brassolida?, Heliconidse, and Eurygonidae, 

 with a fourth, Erycinidae, which only extends into the Nearctic 



