SOUTHERN FROGS. 



275 



there is never any expansion of these extremities. The outer metatarsals are 

 completely united, and the skull is remarkable for the extent to which ossifica- 

 tion is carried out. In some species, such as the Brazilian horned frog (C. boiei), 

 the upper eyelid is produced into a horn-like appendage ; but in others, like the 

 Argentine horned frog (C. ornata), this is little developed and scarcely noticeable. 



The largest representative of the genus is the above-mentioned Brazilian 

 horned frog, which attains as much as 8 inches in length, and is one of the most 

 handsomely ornamented of the genus. The smaller Argentine species represented 

 in our illustration differs from it by the upper eyelid being only slightly 

 pointed and triangular, as well as by the presence of a bony shield on the back. 

 The skin is covered with tubercles above and granules below ; the general colour of 



ARGENTINE HORNED FROGS, OR ESCUERZOS (liat. size). 



the upper-parts being yellowish or greenish, with large olive spots surrounded by 

 light-coloured or golden margins, while there are sometimes wine-red lines between 

 the spots. These frogs, or escuerzos, as they are locally called, are abundant in 

 many parts of Argentina, and in damp weather may be met with crawling about 

 among the grass in numbers, after the manner of toads. They are exceedingly bold 

 and ferocious, flying fiercely at anyone who attacks them, and maintaining their 

 hold with the tenacity of a bull-dog, at the same time uttering a kind of barking 

 cry. On other occasions they give vent to a peculiarly deep bell-like note. "W hen 

 in repose, escuerzos are in the habit of burying themselves in the soil with only the 

 top of the back exposed, in which state they are almost in\ isible. In this position 

 they lie in wait for their prey, which includes other frogs, birds, and small mammals ; 

 and at times they capture and attempt to swallow objects to, 1 large for their capacity. 



