SUB-FAM. 1. ENGYSTOMATINAE.–_Without teeth in the upper jaw._–Although there are only about 60 species known, these have been grouped into more than two dozen genera, many of which are represented by one or two species only. The range of this sub-family is peculiar, namely, Neotropical and Palaeotropical. _Scaphiophryne_ and _Rhombophryne_ are peculiar to Madagascar; _Calophrynus_ occurs in the same island and in the Indian region; _Xenobatrachus_, _Sphenophryne_, _Liophryne_, _Mantophryne_, _Callulops_ and _Xenorhina_ live in New Guinea. _Breviceps_, _Cacosternum_ and _Hemisus_ are confined to Africa, while of _Phrynomantis_ two species live in Africa, and the third in the Malay island of Amboina. Such freaks of distribution indicate either that many of these genera are not established upon very valid characters, or that their respective species are instances of convergent evolution, and do not form natural genetic groups. Many of the members of this sub-family live upon ants and termites, and it is a well-known fact, not restricted to the Anura, that this kind of fare has a peculiar, modifying influence upon the structure of the mouth, teeth, tongue, limbs, and various other organs. In the present case the tongue is not much affected; it is, with few exceptions, more or less oval, not nicked, but free behind; in the Indian _Glyphoglossus_ and in _Rhombophryne_ of Madagascar only is it modified into a rather long and grooved, almost double, apparatus. A very common feature is the small size of the mouth and the formation of a snout, which projects beyond the upper rim of the mouth and beyond the nostrils. Such a prominent and pointed snout is well developed in _Rhinoderma_, _Phryniscus_, _Calophrynus_, _Stereocyclops_, _Hypopachus_ and _Engystoma_. The mouth is very narrow in _Cacopus_, _Glyphoglossus_, _Breviceps_, _Rhombophryne_, and _Hemisus_, all creatures which seem to be confirmed eaters of ants and termites. However, it must not be supposed that the mouth of all the genera is narrow, although this character, rather marked in _Engystoma_, is now embodied in the name of the family. A peculiar development of the palatal region {226}is possibly correlated with this food. The palate is mostly toothless, but its skin is frequently raised into a transverse fold, between or behind the vomers, and into a second fold in front of the oesophagus; these folds are sometimes rather hard and serrated or denticulated. The palatine bones carry true teeth in _Rhombophryne_, and sometimes in _Callula_; in _Xenobatrachus_ the teeth are reduced to two large pairs. The tympanum is usually hidden.