CLASSIFICATION 141 



This emendation of the Arcifera and Firmisternia was accepted 

 by Cope in his synopsis of the families of Yertebrata (Amer. 

 Xnt ni-iil. xxiii., 1890), except that he still retained his suborder 

 Gastrechmia. 



Since the publication of Boulenger's great work a number of 

 forms have been discovered which, from the characters of their 

 dentition, have necessitated the establishment of certain new 

 families, namely, Ceratobatrachidae and Genyophrynidae ; and 

 Boulenger was the first to recognise that the taxonomic value 

 of the mere presence or absence of teeth in the jaws had been 

 overestimated. I therefore propose using it as a character 

 distinctive of the sub-families only, thereby reducing the number 

 of families, relying first (leaving the Aglossa aside) upon the 

 firmisternal or arciferous condition of the pectoral arch, secondly 

 upon the dilated or cylindrical shape of the sacral diapophyses, 

 thirdly upon the dentition. Blindly consistent application of 

 these principles would reduce the Phaneroglossa to four families 

 only, namely Ranidae, Engystomatidae, Cystignathidae and a 

 fourth family comprising all the Arcifera with dilated sacral 

 diapophyses. This would obviously be wrong. We have there- 

 fore to resort to other additional characters or rather peculiarities. 

 The opisthocoelous character of the vertebrae and the possession 

 of distinct ribs, together with the disc-shaped tongue, sepa- 

 rate the Discoglossidae and justify their retention as a family. 

 The Hylidae are marked off by the claw -shaped terminal 

 phalanges, but the remaining forms, comprising the Bufonidae 

 and Pelobatidae, cannot be separated except by their dentition, 

 and I plead guilty of inconsistency in retaining them as separate 

 families. 



After all, our classification may not represent the natural 

 system, and it may be nothing but a convenient key. 



When we have eliminated the characters of the vertebrae, the 

 dentition, the claw-shaped phalanges and the adhesive discs, it 

 may well be asked what characters remain. The firmisternal is a 

 further, higher modification of the older, more primitive arciferous 

 condition. The difference between the dilated and cylindrical 

 shape of the sacral diapophyses is in not a few cases very slight, 

 and there are various, most suggestive exceptions. The presence 

 or absence, size and shape of the omosternum and metasternum 

 are of very limited taxonomic value, not always applicable to all 



