XX I] ANUEA 545 



Order II. Anura. 



The Anura or Batrachia are at once recognised by their broad, 

 flattened, tailless bodies and their powerful hind-limbs. 



Structure. m . 



These limbs are not only efficient in jumping but also in 

 swimming, and the toes are connected with one another by a thin 

 web of skin in order to aid them in performing this function. The 

 toes are stretched apart in the back stroke to present a large surface 

 to the water, in the forward stroke they are folded together and 

 offer little resistance. 



Anura are much more abundant than Urodela and are found all 

 over the world, whereas the Urodela are restricted to the Northern 

 hemisphere. They are in fact the dominant Amphibia of the present 

 day, but they are highly specialised, and the Urodela give a much 

 better idea of the relation of the Amphibia to the Fishes on the one 

 hand and the Reptiles on the other, for which reason Molge was 

 selected as the type. 



Besides the absence of a tail, the powerful character of the 

 hind-limbs and the differences in the skeleton connected therewith, 

 Anura differ from Urodela in the skull' and jaws, in the pectoral 

 girdle, in the heart and lungs, and in the kidneys, genital organs 

 and development. 



Two genera and four species of Anura occur in the British Isles. 

 Rana temporaries, the Common Frog, and R. esculenta, the Edible 

 Frog, represent the Family RANIDAE, but the latter of these two 

 species is very possibly not indigenous but may have been introduced 

 from the continent, while the BUFONIDAE or Toads are represented 

 by Bufo vulgaris, the Common Toad, and by B. calamita, the 

 Natterjack, which occurs in numbers in certain restricted localities, 

 as a rule those with a sandy soil. 



As the Common Frog, Rana temporaria, is easily attainable, 

 The Fro ^ e principal points in which it differs from Molge 



will be briefly, described. 



The animal when at rest normally squats on its haunches, 

 supporting itself slightly on its palms. Under these circumstances, 

 the pelvic girdle makes a considerable angle with the vertebral 

 column and the powerful iliac bones raise the skin of the back into 

 a well-marked hump, the so-called sacral prominence. 



The gape is enormous, and is caused by the lower end of the 

 suspensorium, or part of the skull to which the lower jaw is 

 s. & M. 35 



