294 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1951 



snakes, one of which, the southern diamondback, reaches more than 8 

 feet in length; the coral snakes of the south; and the iguanoid lizards, 

 including the curiously flat and broad horned toads, which squirt a 

 drop of blood from above the eye when alarmed. In the southeast 

 lives the alligator, and in the extreme south the American crocodile. 



Amphibians', especially frogs, tree frogs, toads, and in the moun- 

 tains salamanders, become abundant. Worthy of mention are the bull 

 frog, 8 inches long ; among the salamanders in the east the hellbender, 

 2 feet long; several mud puppies, also up to 2 feet long; the congo 

 snakes (Amphiuma) with rudimentary legs, up to 3 feet long ; and the 

 mud eels (Siren) with no hind legs, also 3 feet long. North America 

 is the richest part of the world in salamanders, as South America is 

 in frogs. 



Fishes are very numerous, largely of endemic types such as the nest- 

 building Centrarchidae, the gars (Lepidosteus) , and the bowfin 

 (Amia). Especially interesting are the cave fishes ( Amblyopsidae) , 

 of which four genera with seven blind and colorless species occur in 

 the subterranean waters in the eastern half of the Mississippi Valley, 

 and one genus with two normally colored species with fully developed 

 eyes inhabits the coastal swamps from Virginia to Georgia. These are 

 evidently the remnants of a once numerous and widespread group. 

 The North American catfishes (Ameiuridae) and the suckers (Cato- 

 stomidae) are almost wholly North American, but both families have 

 a representative or two in eastern Asia. 



Insects are exceedingly numerous and diversified; many are of 

 tropical American types, though some are endemic. There are about 

 700 different kinds of butterflies, many of which are large and hand- 

 some. One small butterfly [Feniseca) with African and Asiatic rel- 

 atives is carnivorous in the early stages. Of other invertebrates, the 

 fresh-water mussels (Unionidae) are more numerous and diversified 

 in North America than elsewhere. 



FAUNA OF CENTRAL AMERICA 



The fauna of the mainland of Central America is predominantly 

 South American with an admixture of North American types, espe- 

 cially in the highlands, and a few Antillea» forms. It reflects the 

 diversity of the geographical features, and minor local variants of 

 both South and North American animals are abundant. The fauna 

 of the West Indies is scanty and is composed of types at present largely 

 unrepresented, or but poorly represented, on the mainland. 



Among the mammals of Central America are two species of tapirs 

 that are quite distinct from all other living tapirs though related to 

 fossils found in North America, one ranging from Panama to Mexico, 

 the other found in Guatemala, Nicaragua, and Costa Rica. Spider 



