DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 
o 
o 
But the ideal Protobatrachians came up by the way of the Sucking Fishes (“ Marsipo- 
branchii ”), and grazing the edge of the Chimseroids and ordinary Selachians, developed 
into the larval form (or Tadpole) first. I am under the impression that in many cases 
the tailed gill-bearing condition has only lately been completely departed from, and 
that the anurous form or stage of such a type as Pseudis has only become universal 
in the newer geological times. 
Whilst these tailed forms—-hypothetically the primary condition of the Batrachia 
—have been yielding to terrestrial influences, and undergoing more and more cur¬ 
tailment and general metamorphosis, they have also, from time to time, dropped 
out of their organisation much of their old bony armour ; and that which has been 
retained has become less and less superficial (or “ dermosteal ”). 
They have to a remarkable degree lost their mandibular , and in many cases their 
maxillary teeth also; this has been evidently a correlate of the development over 
the ventral end of the hyoid arch of a peculiar cushioned fold of the floor of the 
mouth—the tongue. As this fold has become a more and more effective prehensile 
organ, the teeth have become less and less useful to the creature, whose succulent 
“ articulate ” or “ molluscous ” food is caught suddenly, and swallowed whole. 
The size of these types has evidently undergone a steady secular diminution ; this, 
and in many cases an exquisite specialisation of the fingers and toes, has all been in 
their favour ; up high in the trees of the forest, and variously painted to resemble their 
surroundings of bark, leaves, and flowers, these marvels are wrought in them by the 
“ Archchemic Sun —them small size, I say, their curiously mimicking coat, and their 
high nestling, give them a chance of life and of life’s enjoyments equal to that given 
to any tribe of animals whatever. 
As in the common living forms now, the dilemma for the larval Batrachian is to 
“transform or perish” in short annual periods; so, I opine, in long-past secular 
periods, again and again, those tribes—the forefathers of our existing kinds—have 
been put to the same extremity of shifting for their lives. 
As the earth was made to be inhabited, and as the evolution of its tribes takes 
place through the harmonious inter-action of the forces within the organisms and the 
influences surrounding them, it has come to pass again and again that the extremity 
of some archaic form has been Nature’s opportunity; its threatened extinction has 
been the occasion of its transformation into a higher kind of being, and the drying up 
of the old waters has been followed by the peopling of the new land with fresh and 
fresh forms, enjoying in many ways “ newness of life.” 
There are two main groups of dwarf forms, namely, the highly developed and 
typical Tree-frogs, and the arrested, low kinds, such as the “ Engystomidee' ” and 
“ Phryniscidse these latter appear to be waifs and strays from old and extensive 
tribes that have gone down in the world and are becoming gradually extinct; the 
“ Hylidse ” (like the smallest “ Carinate ” birds), being Frogs of high degree, are in 
no such danger of extinction. 
B 2 
