there are numerous small species even of them, and also of laud 

 Tortoises. 



The Batrachians, or Amphibians, are very much smaller than 

 the Reptiles ; indeed, there is amongst them but one moderate 

 sized species, the Gigantic Salamander of Japan, and this rarely 

 exceeds three feet in length. 



The Fishes are all aquatic ; and the only comparison that can 

 be made between them and the higher Vertebi'ates is with those 

 species of the latter which exist under similar conditions to the 

 former. The Fishes fall short of the size of the Whales, Sperma- 

 ceti Whales, and Grampuses. 



The Dolphins, Porpoises, Dugongs, Manatees, Walruses, and Sea 

 Elephants, are all of a size which would be considered very large 

 among Fishes. 



If a closer examination is made of the Mammalia alone, the 

 rule shews itself with force ; not, perhaps, that the highest groups 

 always contain larger species than the lowest, although, speaking 

 roughly, that even is the case to a great extent. 



Man attains a larger size than any of the Antlu'opoid Apes, and 

 of these the Gorilla, Chimpanzees, and Orangs are larger than 

 any other Quadrumana. 



The Dog is the largest of the Canidae, although, by artificial 

 selection, some small varieties have been obtained. 



The Elephant is by far the lai'gest of all the Pachyderms, and 

 is probably the most intelligent animal in existence. 



The Horse and the Ass are highly developed and large animals, 

 and to these may be added the Camel, Ox, Buffalo, Sheep, and 

 Goat. 



When these are compared with the Rodents, all lowly developed 

 animals very numerous in species, but containing only one large 

 species, the Capybara, and that both aberrant and also aquatic, 

 the rule under consideration is exhibited with great force. 



Most of the Rodents are very small ; the familiar Mouse, Rat, 

 Squirrel, Rabbit, Hare, Guinea-pig, cannot for one moment be 

 thought large when compai'ed with the higher Mammalia, and 

 even amongst these Rodents the rule holds good. We all know 

 how far more easy it is to capture the small ilouse than it is to 

 trap the larger and more intelligent Rat. 



The Placental Mammalia are also much larger, taken collec- 

 tively, than the Implacental or Marsupial. 



The largest of the latter, the great Kangaroo, is by no means a 



