THE SURINAM TOAD. 2J 



which inhabits Guiana and several provinces of Brazil. The most 

 remarkable feature in this Batrachian is its manner of reproduction. 

 It is oviparous : and when the female has laid her eggs, the male 

 takes them, and piles them on her back. The female, bearing the 

 fertilised ova, reaches the marshes, and there immerses herself; but 

 the skin which supports her future progeny soon becomes inflamed, 

 erysipelatous inflammation follows, causing an irritation of the integu- 

 ment, which continues till all are absorbed into the skin. 



The young are rapidly developed in these dorsal cells, and are 

 extricated at a less advanced stage than almost any other vertebrate 

 animal. After extrication, they grow rapidly, and the chief change 

 of form is witnessed in the gills. As to the mother Batrachian, it is 

 only after she has got rid of her progeny that she abandons her 

 aquatic residence.* 



The Batrachians differ essentially from all other orders of Reptilia. 

 They have no ribs ; their skin is naked, being without scales. The 

 young, or tadpoles, when first hatched, breathe by means of gills, being 

 at this stage quite unlike their parents. These gills, or branchiae, 

 disappear in the tailless Batrachians, as the Frogs and Toads. 

 In the tadpoles the mouth is destitute of a tongue, this organ only 

 making its appearance when the fore limbs are produced. The 

 habits also change : the tadpole no longer feeds on decomposing 

 substances, and cannot live long immersed in water ; the branchiae 

 disappear one after the other, by absorption, giving place to pul- 

 monary vessels. The principal vascular arches are converted into 

 the pulmonary artery, and the blood is diverted from the largest of 

 the branchiae to the lungs. In the meantime the respiratory cavity is 

 formed, the communicating duct advances with the elongation of the 

 oesophagus, and at the point of communication the larynx is ultimately 

 developed. The lungs themselves extend as simple elongated sacs, 

 slightly reticulated on the inner surface backwards into the abdo- 

 minal cavity. These receptacles being formed, air passes into and 

 expands the cavity, and respiration is commenced, the fore limbs are 

 liberated from the branchial chambers, and the first transformation is 

 accomplished. 



The alleged venomous character of the Common Toad has been 

 altogether rejected by many naturalists ; but Dr. Davy found that 



* The same phenomena occur, with certain variations, in some other American 

 Batrachians, as the NototreTna marsupiatum of Mexico, and the Notodelphys ovifera 

 of Venezuela. In the Alytes obstetricans of France, Switzerland, and the Rhine 

 district, the ova (about sixty in number) adhere to the hind-legs of the male 

 parent ! — Ed. 



