152 



THE AFRICAN BULL-FROG. 



of the Frogs is greatly affected by the locality in which they are at the time placed. 

 The Tree-Frogs are more subject to this change of color than the ordinary species ; 

 but even our common English Frog is well known to alter from yellow to brownish 

 black in a very short space of time. This change is produced by some mental emotion 

 acting upon certain masses of pigment or coloring matter in the skin ; and for a farther 

 elucidation of the subject, I must refer the reader to my " Common Objects for the 

 Microscope," where the pigment masses are drawn as seen through the microscope, 

 and their peculiar action explained. 



ONE of the most singular members of this group of animals is the PARADOXICAL 

 FROG (Pseudis paradoxa). 



This curious creature is a native of Surinam and South America, and is remarkable 

 for the enormous size of the larva, or tadpole. As a general rule, and indeed, as might 

 be expected, the generality of the batrachians are smaller in their larval than in their 

 adult state ; the tadpole of the common Frog being a good example. But the Para- 

 doxical Frog exhibits a phenomenon which is perhaps found in none of the higher an- 

 imals, though common enough among the non-vertebrated beings, and is less in its 

 adult state than in its preliminary form of tadpole. 



The tail of this tadpole is exceedingly voluminous, and the body has other envelopes 

 or appendages, which, when thrown off as it proceeds to its perfect state, reduce the 

 bulk so greatly that the earlier observers thought that the creature reversed the usual 

 order of nature, and from a Frog became a tadpole. Some persons went even farther, 

 and said that it was changed from a Frog into a fish. The appropriate title of 

 Paradoxical was given to it in allusion to this opinion. 



Strange, however, as this phenomenon may appear, and remarkable as it undoubtedly 

 is, it finds abundant parallels in the insects, where the larva is often of greater bulk 

 than the perfect insect, or imago, as it is technically called. We may take for ex- 

 ample the common silkworm, where the caterpillar is extremely large when compared 

 with the moth into which it afterwards changes ; or that great, fat, bulky, subterranean 

 grub, which eats continually for three years, becomes so obese that it is forced to 

 lie on its side, and afterwards turns into the neat, compact, and active little cockchafer. 



The color of the Paradoxical Frog is greenish, spotted with brown, and streaked 

 irregularly with brown along its legs and thighs. The snout is tapering, and rather 

 pointed in front. 



OUR next example of the Ranidae is the AFRICAN BULL-FROG. 



This fine species is spread over the whole of Southern Africa, but is found most 

 plentifully towards the eastern coast, where it always frequents springs, pools, or the 

 vicinity of fresh water. It is most impatient of drought, and when a more than usually 

 dry season has parched the ground and rendered the hot soil uncomfortable for the 

 delicate skin of the creature's feet and abdomen, these Frogs are said to congregate in 

 the pools in great numbers, and just before the water has quite dried up, to burrow 

 deeply into the soft mud and there lie until the next rains bring the welcome moisture. 



Fifty of these large Frogs have been seen gathered together in one little pool, far 

 from any other water. ,It is, moreover, evident that they must have some place of 

 concealment, for they are sure to appear in great numbers after a few heavy rains, 

 and it is quite consistent with probability that they should possess a simple and 

 obvious method of preserving their lives during the frequent droughts of the climate 

 in which they reside. 



Dr. Livingstone mentions this fine species in his well-known work on Southern 

 Africa. " Another article of which our children partook with eagerness was a very 

 large Frog, called ' Matlame'tlo.' 



These enormous Frogs, which, when cooked, look like chickens, are supposed by the 

 natives to fall down from thunder-clouds, because after a heavy shower the pools which 

 are filled, and retain water a few days, become instantly alive with this loud croaking 

 pugnacious game. This phenomenon takes place in the driest parts of the desert, and 

 in places where to an ordinary observer there is not a sign of life. 



