Batkachians.- 



-REPTILES. 



-Fr.OGs. 



87 



ORDER OF BATRACIIIANS (Batraciiia). 



In all the Batraciiia the skin is soft and smooth, and 

 generally more or less moist. It possesses the power of 

 secreting fluid, and thus materially assists in effecting 

 those changes in the blood which in otiier animals are 

 performed by the lungs or gills. All tlie Batrachians, 

 the history of which we are well acquainted with, 

 undergo a scries of transformations or metamorphoses 

 while advancing from youth to maturity. The young 

 enter life under an entirely different form from tliat 

 which they are afterwards to assume. At lirst emerg- 

 ing from the egg, and for some considerable time after- 

 wards, their form and structure are essentially similar 

 to those of fishes. They have an elongated body, no 

 feet, a laterally compressed tail, and external gills. 

 The mouth, wliich is small, is furnished with horny 

 hooks or teeth for the separation of vegetable matter, 

 and they have a small tube on the lower lip for attach- 

 ing themselves to aquatic plants. In this state they 

 are known by the name of tadpoles. At a certain 

 period of their growth a gradual change takes place. 

 In some the external gills disappear, and become 

 covered with a membrane, being placed in a sac under 

 the throat. The creature now breathes as a fish. Soon 

 the hinder limbs begin to make their appearance, 

 showing themselves near the origin of the tail ; the 

 anterior limbs are then put forth. The lungs, which 



hitherto have been rudimentary, now begin to bo 

 developed ; the gills are removed by absorption, and 

 the animals respire like perfect reptiles. 



All the Batrachians, in their first state especially, 

 swim well, and the greater number can also, at least in 

 the adidt state, walk npon the earth, and can climb and 

 even leap with great facility. The form of their body 

 indicates as it were beforehand the nature of their 

 movements. Thus, for example, all those which pre- 

 serve the tail in their adult state walk only slowly ; 

 they can merely drag their bodies along the gTound, 

 and usually live in the water, as the Salamanders. 

 Tliose, on the contrary, which lose this member, as 

 the Frogs, walk on the ground, climb trees, and leap 

 with great agility. Taking these tJicir habits into con- 

 sideration, as well as their form when in the adult 

 stage of existence, naturalists have in consequence 

 divided the whole Order of Batrachians into two sub- 

 orders or large groups. The first is the sub-order 

 Salientia or Leaping Batrachians, by many authors 

 called Anoura, or Tailless Batrachians ; and con- 

 tains the Frogs and Toads. The second sub-order 

 is that of the Guadientia, or Walking Batrachians, 

 called by many authors Ukodela, or Tailed Batra- 

 chians ; and contains the Salamanders, and Tritons or 

 Newts, &c. 



Sub-order I.— BATRACHIA SALIENTIA, or ANOURA (Tailless Batrachians). 



In the catalogue of the species of the Bulrachia 

 Salientia in the British Museum, compiled by Dr. 

 Giinther, and wliich amount to the number of two 

 hundred and eighty, this suborder of Batrachians is 

 divided into three groups, according to the presence 



Fig. 23. 



Mouth of Polypcdatcs Sclilogelii — to show form and structure of 

 tongue of the Opisthoglossa. 



or absence and form of the tongue. The greater num- 

 ber have their tongue, which is fleshy and somewhat 

 bifurcated at the tip, adhering to the jaw in front, 

 whilst it is more or less free behind — forming the 

 group called Opisthoglossa, or Front-tied tongues — 

 fig. 23. A few have this member free in front, and 

 form the group Proteroylossa ; whilst there is a small 

 number again which have no tongue at all. Tliese are 

 called Ar/lossa. 



Tlie first group, tlie Front-tied tongues {Opintho- 

 gbssa), contains more than seven-eighths of the whole 



number of species, and is divided into sections accord- 

 ing to the structure of their toes ; one set having tlie 

 toes sharp at their extremities {Oxi/daclyla), while 

 another has the tips of the toes dilated into small pads 

 {Platydactyla). The sharp-toed section is composed 

 of the true frogs and toads, Raiiina and Bvfonimi, 

 while the flat-toed section contains the tree-frogs, 

 Hyliiia : — 



Ranina, or Frogs. 



The Frogs are in general of a slight, thin form, with 

 the hind legs much longer than those in front. "When 

 in a state of repose on the ground, they carry their 

 head very liigh, and their hind legs are then doubly 

 folded on themselves, forming an angle of 45° with the 

 length of the body. The muscular system is well 

 developed, and the muscles of the thigh and leg parti- 

 cularly so, presenting a gi'eat analogy with those of 

 man. They possess a great degree of elasticity, and 

 in consequence of this, the leaps wliiidi these animals 

 take when suddenly roused or alarmed, are very great, 

 extending sometimes, it is said, over a space moro 

 than fifty times the length of its body. Frogs gene- 

 rally feed upon the larva; of aquatic insects, worms, 

 small mollusca, &c. ; and they are sure to select for 

 their prey an animal which is alive and in motion. 

 They always reject dead animal matter. To obtain 



