_Remarks._--The systematic status of _Cauphias crassus_ Brocchi has been in doubt since the time of the original description. Brocchi (1877:130) stated: "Les dernieres phalanges sont obtuses, tronqués a leur extrémité antérieure." Brocchi placed the species in his genus _Cauphias_ (type species, _C. guatemalensis_), which he considered to be related to _Hylodes_ ( = _Eleutherodactylus_ in the sense used by Brocchi); he thereby placed _Cauphias_ in his Hylodidae ( = Leptodactylidae, in part). This idea of relationships was perpetuated by Barbour (1927:96), who reported on the second known specimen of _Cauphias guatemalensis_ and stated: "When I dissected the sternum I was at once struck by its similarity to Noble's figures of transitional types between arciferal and firmisternal forms. The _Cauphias_ sternum recalls some of his figures for _Sminthillus_ and _Eleutherodactylus_. This genus is probably most closely related to the latter and has probably become highly modified to meet some peculiar environmental condition or on account of some specialized habits as yet unknown." Kellogg (1932:118) placed _Cauphias_ in the Leptodactylidae and stated that the terminal phalanges are T-shaped. Hartweg (1941:1) considered _Plectrohyla_ to be the correct generic name for _Cauphias guatemalensis_; he thereby relegated _Cauphias_ to the synonomy of _Plectrohyla_. Hartweg (1941:9) further showed that the terminal phalanges of _Plectrohyla guatemalensis_ were not T-shaped and that intercalary cartilages were present. Thus, he correctly concluded that _Plectrohyla guatemalensis_ (and _P. crassa_ by implication) was a member of the family Hylidae. Stuart (1942:6) followed Hartweg's allocations and further suggested that _Plectrohyla crassa_ might be the same species as _Hyla robustofemora_ Taylor. In his description of _H. robustofemora_ Taylor (1940:392), who had not examined the type of _Cauphias crassus_, stated that were it not for the statements of Brocchi and Kellogg that _C. crassus_ has T-shaped terminal phalanges, "I might suspect I had before me a specimen of _Cauphias_ closely related to _crassum_." I have compared the type of _Cauphias crassus_ with that of _Hyla robustofemora_. With the exception of the minor differences mentioned in the preceding section on variation, the specimens are alike, leaving little doubt that they represent the same species. The statements of Brocchi and Kellogg to the contrary, the type of _Cauphias crassus_ possesses intercalary cartilages between the penultimate and terminal phalanges; the latter are not T-shaped, but as in the type of _Hyla robustofemora_, resemble those typical of _Hyla_. On the basis of the morphological characters, as pointed out for _Hyla robustofemora_ by Taylor (1940:392), _Hyla crassa_ is a member of the _Hyla bistincta_ group. _Distribution._--This species is definitely known only from a small stream at an elevation of 2300 meters in the mountains of central Oaxaca (Fig. 4).