196 ESSENTIALS OF ZOOLOGY 



same time launching the tongue, which is the instrument of 

 capture. 



The enemies of frogs are many, and range from insect 

 larvae and fishes in the water to snakes and birds on land 

 and in water, but man makes a great demand on frogs. Species 

 of Eana are used for food on the continent of Europe (R. 

 esculenta) and in America (several species), and large numbers 

 are employed in zoological and physiological laboratories. * 



EXTERNAL CHARACTERS. Eana temporaria is distinguished 

 by the black patch behind the eye. The colour generally is 

 yellow or brown with patches of brown or black, and it is 

 variable and under control. The skin is smooth and moist. 

 There is no skeleton associated with the skin, but such is 

 developed in the South American Ceratophrys. 



The head is broad and flat and passes into the body without 

 a neck, and there is no tail. The anterior limbs are short, and 

 the digits are not webbed. The posterior limbs are long, and 

 the toes are connected by a web. The hand of the male bears 

 on its inner aspect a swelling which expands in the breeding 

 season into a dark brown glandular cushion for clasping the 

 female. 



On the dorsal aspect of the head there will be seen the 

 paired nasal openings, the prominent eyes, each with a thick 

 upper and a membranous lower eyelid, and the rounded area 

 in the black patch, which is the tympanum of the ear there 

 is no external ear or outer passage. The mouth is a wide 

 opening occupying the margin of the head, and if it be opened 

 and distended several important features of structure are 

 brought into view. The margin of the upper jaw is formed 

 by the premaxillae and the maxillae, which bear a row of small 

 pointed teeth. So also do the vomers, which lie immediately 

 behind the premaxillae. Just externally to the vomers the 

 roof of the mouth presents the inner openings of the nasal 

 passages, which thus extend almost directly from the surface 

 of the head into the roof of the mouth. In other words, the 

 nasal passages are not carried backwards with the formation 

 of a palate. The centre of the roof of the mouth is occupied 



1 1920. Wright, Frogs, their Natural History and Utilisation. U.S. Fish. 

 Bur. Doc. No. 888. 



