XXX INTRODUCTION. 



tongueless Anura, has star-shaped extremities to the fingers, which are 

 probably sensitive tactile organs. Dactylethra, the clawed frog of Africa, 

 belonging to the same group, has claws on its toes. Of the group possess- 

 ing tongues, Opisthoglossa, those living in trees have fleshy bulbs or disks 

 on the ends of the digits, by means of which they cling to smooth surfaces. 

 The tree frogs, Hyliclce, exhibit this structure at its greatest development. 

 Many species of the order have horny processes on the feet for burrowing. 

 The males of some develop horny claws or tubercles on the inside of the 

 thumbs or on the breast in the coupling season. 



All of the Anura begin life as tadpoles, breathing and moving like fishes. 

 They undergo a complete metamorphosis in taking on the form of the adult. 

 Fertilization takes place externally, the male grasps the female tightly 

 around the body, and the spermatic liquid is emitted as the eggs are 

 extruded. Usually the males are smaller and more numerous. Habits 

 vary much in regard to care of eggs. Our common Toads and Frogs leave 

 them to care for themselves in the pools in which they are laid. The male 

 of the obstetric Toad, Alytes, carries the eggs until they are about to hatch 

 attached to his thighs, and then he enters the water. The male of the 

 Surinam Toad, Pipa, places them carefully on the back of the female, and 

 the skin rises around each, enclosing it in a little cup, within which the 

 metamorphosis is effected. Nototrema carries the eggs in a pouch on the 

 hinder part of the back. Hylodes martini censis lays the eggs in the axils 

 of leaves, and transforms so soon after hatching that it can hardly be said 

 to have a tadpole stage. The larva of the Bull Frog, Rana catesbijana, 

 remains a tadpole from one to several years. Many of the young feed 

 upon vegetation for a time, afterward becoming carnivorous. M. Fernand 

 Lataste has recently called attention to series of pectinate fringes or teeth 

 outside of the horny lips of the tadpoles, and M. Heron-Roy er finds so 

 much variation in the various genera as to aid him in classification. 



As the lungs and limbs develop, the intestine is shortened and [the tail 

 resorbed. The lower jaws are toothless.* As in toads, Bufo, some are 

 entirely without teeth in the adult forms, and others, as the frogs, Bana, 

 are in possession of teeth on upper jaws and on the roof of the mouth 

 between the inner nostrils. The eyes are most often prominent and very 

 keen. The inner eyelid is transparent. An East Indian genus, Mega- 

 lophrys, and another from South America, Ceratojjhrys, have supraciliary 



* Except in Amphignathodontidce and Hemiphraclidcs, 



