438 AMPHIBIAORDER LECAUDATA. 



in water. One member of a Tropical American genus of this family namely 

 Phyllobates trinitatis, of Trinidad and Venezuela is remarkable 011 account of 

 its curious nursing habits. The tadpoles are provided with sucking-discs on 

 the mouth, by means of which they attach themselves to the back of their 

 female parent, and are thus carried about in safety. As many as from twelve 

 to eighteen tadpoles may sometimes be found thus clinging to one frog. A 

 similar mode of attachment occurs in one species of the under-mentioned 

 genus Deiidrobates y but in this case this mode of locomotion seems to be 

 resorted to only when the ponds in which the individuals have bred dry up. 



In addition to the members of the genus Rhacophorus, there are many 

 other frogs which have taken to an arboreal life, and so much do these 



resemble one another in external appearance that it is pro- 



Family bable any non-scientific observer would regard all of them 



Dendrobatidce. as being very closely allied. Not so that dreadful personage 



the anatomist, who tells us that while the members of one 

 family conform in the structure of the bones of the chest to the sub-order 

 now under consideration, all those .of another family to be mentioned 

 later have a totally different conformation of this region. Accepting this 

 distinction, we must regard the Tropical American tree-frogs of the genus 

 Dendrobates, and those belonging to the nearly allied Malagasy genus Mantella, 

 as forming a family by themselves. From the frogs of the family Ranidce 

 the Dendrobatidce are distinguished by the absence of teeth both in the upper 

 jaw and on the bones of the palate. In both genera the toes are unwebbed, 

 and terminate in small adhesive discs, but whereas in Mantella the tongue is 

 notched at the tip, in Dendrobates it is entire. One species of the latter 

 genus (D. tinctorius) is remarkable for the brilliancy and variability of its 

 coloration; while it is further noticeable as being less arboreal than its con- 

 geners, generally frequenting low herbage or ground strewn with dead leaves. 

 As already mentioned, another species carries its tadpoles clinging to its back 

 from pool to pool in seasons of drought. 



Another nearly allied family of frogs is distinguished from the last by the 

 expansion of the extremities of the horizontal transverse processes of the 



sacral vertebra ; both 



Family groups agreeing in the 



Engystomatidce. absence of teeth in 



the upper jaw. These 

 frogs present great variation in the 

 structure of the bones and cartilages 

 forming the chest ; the typical genus 

 Engystoma, together with Cacopus and 

 several others, showing the absence 

 of the bones known as precoracoicls 

 a feature rare in the sub-order. This 

 family may be regarded as essentially 

 a southern one, its geographical range 

 embracing Africa, Madagascar, the Fig. 3. Cacopus systema. 



Malayan Peninsula and Islands, India, 



the south of China, New Guinea, and South and Central America. Two 

 species of the typical genus extend, however, into North America as far as 

 Mexico and Carolina. Nearly a score of genera are included in the family. 

 Among these, a considerable number are characterised by the extremely 

 small relative width of the opening of the mouth ; and it is probable 



