2 Mr. W. K. PARKER ON THE STRUCTURE AND 



charactei-s as are easily seen by the Zoologist is to build upon a sandy foundation ; none 

 will be more ready to acknowledge this than those who are most famihar with the group. 



Even the cranial characters, which lie deeper down, are extremely variable, so that 

 in formulating them for any division or sub-division of the Order it is always necessary 

 to give some quaUfication of the scheme, and to say that " as a rule " such and such 

 modifications of structure exist in the group under notice. 



Our "genei'a" suffer from this weakness; and in some cases, notably in the great 

 genus Rana, there are morphological modifications and variations such as are not to be 

 seen in whole groups of Families in the Osseous Fishes. 



On the whole, my own views correspond very accurately with those of my friends 

 Messrs. GuNTHER, MivART, and Wallace (whose works are referred to in the biblio- 

 graphical list) ; they, I am satisfied, will be struck with the evidence here shown of 

 the common origin of groups of the Batrachia that now are very widely dispersed, and 

 marked by every variety of external character. 



For there can be no doubt that these cmious fishy air-breathers are, as Mr. Wallace 

 has suggested to me, a very ancient kind of Vertebrates. They have not struggled 

 for lile through one but through many epochs ; tliey have been put to every kind of 

 shift to live, and with infinite readiness and adaptabihty they have become aU things 

 to all conditions. 



Here, undoubtedly, we get hght upon the mystery of the great perfection of the 

 various organs seen in the members of so lowly a group ; for they are mere anamniotics 

 at the best, and theii' upspring has been from some of the lowest of the Vertebrate 

 stocks. 



In every kind of facility for motion, in organs of sense wonderfully perfect, in power 

 of speech and of song, and in instincts and habits innumerable, the Frogs and Toads 

 teach the order, and anticipate the life of the peopled kingdoms of the nobler ti'ibes 

 that have risen above them in the scale. 



The Salamandrian tribes ("Urodela") have branched up and beyond the "Dipnoi" 

 {Lepidosiren, Ceratodus), and more or less, as a i-ule, lose their gills after a tune, 

 acquiring, in each type, a fenestral passage and a stapedial plug to their ear-capsule. 



They also, in harmony with their more and more terrestrial habits, acquire a 

 rudimentary larynx, so that the beginnings of the better kinds of organs of hearing 

 and of voice are found in them. 



But the Batrachians, springing from another part of the " stock," and indeed from 

 a far lower " node," rise high above the Salamandrians in the metamorphosis of their 

 organs, especially those of voice and hearing ; their general intelligence and their 

 gymnastic powers are also of a much higher kind. 



Supposing tlie Urodeles to have arisen from some archaic forms of the " Dipnoi," 

 the height in the scale of such douljle-breathing Fishes must have corresponded very 

 closely with the Crossopterygii, and these again arc manifestly a mere subdivision of 

 the a;reat " Ganoid " order. 



