SUPPRESSED METAMORPHOSIS. 



485 



As an example of a suppressed metamorphosis, due ap- 

 parently to a radical difference in the physical environment 

 of the animal, may be cited the case of a tree-toad in the 

 island of Guadaloupe. There are no marshes on this island, 

 consequently in a species of Hylodes the development of 

 the young is direct ; they hatch from the eggs which are 

 laid under moist leaves, without tails, and are otherwise, ex- 

 cept in size, like the adults. On the other hand, a tree-toad 

 of the island of Martinique (Hylodes Martinicensis, Fig. 

 436) has tadpoles, which it carries on its back. The female 

 of Nototrema marsiqjiutum Dumeril and Bibron, of the 

 Andes, has a marsupium or sac on its back in which the 

 young are carried. The Notodelphys 

 of South America has similar habits ; 

 for example, the female Opisthodel- 

 pliys (Notodelpliys) ovifera has a dor- 

 sal sac a centimetre deep in which 

 the eggs are carried. In the young 

 of this and of Gastrotlieca also of 

 Central America, Peters found traces 

 of external gills. The Pipa, or Suri- 

 nam toad (Pipa Americana Laurent), 

 which has no tongue, neither teeth in 

 the upper jaw, has similar breeding 

 habits. In this interesting toad the 

 young, according to Prof. Wyman, 



are provided with small gills, which, however, are of no 

 use to them, as the tadpoles do not enter the water, but are 

 carried about in cavities on the back. The eggs are placed 

 by the male on the back of the female, where they are 

 fertilized. The female then enters the water ; the skin 

 thickens, rises up around each egg and forms a marsupial 

 sac or cell. The young pass through their metamorphosis 

 in the sacs, having tails and rudimentary gills ; these are 

 absorbed before they leave their cells, the limbs develop, 

 and the young pass out in the form of the adult. 



The toad (Bufolentiijinosus Shaw) is exceedingly useful as 

 a destroyer of noxious insects. It is nocturnal in its habits ; 

 is harmless, and can be taken up with impunity, though it 



Fig. 436. The Martinique 

 Tree-toad carrying the young 

 on its back. 



