DEVELOPMENT OF THE SKULL IN" THE BATRACHTA. 45 



Leaving out of question mere size, form, and degree of ossification, we have only 

 the followhig things really worthy of notice, viz. : — 



1. Thei-e is no division of the upper "fontanelle." 



2. There are no "septo-maxillaries." 



3. The " quadrato-jugal " largely ossifies the lower part of the suspensorium. 



4. The " supra-stapedial" is very short. 



5. The horns of the "annulus " are wide apart. 



11. liana tigrina. — Adult female ; 5^ inches long. Ceylon. 



This was a large specimen, but not equal to some examined by Dr. Gunther.'''' In 

 coming next to this kind I have passed from the smallest to the largest of the Frogs 

 of India. 



As in the last, I have to be careful to distinguish those cranial characters that are 

 due to mere size from those that lie deeper, and are of more importance. 



Of this I am certain, viz. : that although there is a special density and strength in 

 the bony elements of the larger skulls, yet that is not necessarily connected with an 

 extensive and generalised ossification, which, in some cases, shows most in the dwarfed 

 kinds. The last species is an instance at hand, for its endocranial landmarks are 

 much more obliterated than in this gigantic species. 



In the largest specimens the skull cannot come far short in size of that of EaiKi 

 pipiens ; it is a stronger structure, and the cranium proper is much larger in proportion 

 to its facial outworks (compare Plate 6, figs. 1-3, with Plate 8, figs. 1-4). 



The two differ, however, in a much more important point, for this is a severely 

 typical kind ; the American Bull-frog, on the other hand, is very archaic or generalised. 



Although I have taken the medium-sized Common Frog as the best typical form, 

 I do, nevertheless, consider that in Eana tigrina and in the helmeted Frogs (e.g., 

 Ceratophrys and Calyptocephalus) we come across the most perfect examples of 

 Batrachian cranial architecture ; moreover, they are not deficient in respect of morpho- 

 logical characters that are deeper than, and almost independent of, mere size and bulk. 



The general outline of this skull (Plate 6, figs. 1-3) is more than half of an oval, 

 rapidly narrowing towards either end, as the outline of the Hen's egg does towards 

 one end. 



The whole form is broad behind, but narrowing rather rapidly forwards ; the length 

 of the skull itself as compared to its greatest breadth is as 7^ to 9, but if the 

 measurement be made from one quadrate condyle to the other, as 8 to 'J, for these 

 hinges lie some way behind the occipital hinges. 



The ovoidal occipital condyles (oc.c.) are well seen in both the upper and lower 

 aspects, for they are large and turned over the edge of the occipital floor, so as to fit 

 deeply into the atlantal concavities — a thing answering to the great strength of this Frog. 



These condyles are separated by an emarginate tract less than their own width ; 

 * He gives 6 to 7 inches, mine was therefore only three-fourths the size of the largest. 



