DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 1:30 



form ; and these things are not the same, although they often co-exist in the same 

 species. 



The great difference between the skull of this kind and that of Pelohates partly 

 arises from the Bufonine stoutness of the latter, and the ITyline delicacy of the former ; 

 and this in general form as well as in the internal histological differences. 



The skull of Pelohates is as much overwrought, in comparison of the " norma," 

 as that of Bomhinator is underwrought ; moreover, the fonner has a rudimentary 

 columella, whilst Bomhinator has none. 



Pelohates is as remarkable in showing ichthyic bony patches in the cerato-hyals as 

 Bomhinator in the basi- and hypo-branchials. Bomhinator, in its skull, looks a little 

 towards Dactylethra—tlnit is, in the condition of the nasal capsides ; and it is, for the 

 most part, like a young typical Frog. 



Its divergence from the last-mentioned species, or the tyjie, is seen in the following 

 particulars : — 



1. The fontanelle is wide open, through the arrest of the roof-bones. 



2. The ossification of the occipito-auditory regions is continuous. 



3. The occipital condyles are supew-posteYior, 



4. The nasal capsules are almost entii'ely deficient in their roof-cartilage along the 

 septal region. 



5. There are no septo-maxillaries. 



6. The investing bones are all feeble, except the vomers. 



7. There is no annulus tympanus, 



8. The Eustachian passage is a very small diverticulum, 



9. There is no columella. 



10. There is no palatine bone. 



11. The coronoid process of the "articulare" in the mandible is unusually distinct, 

 and there is an "endosteal" articidare besides the outer plate. 



12. The cerato-hyal is greatly dilated distally, and the notch in front of the basal 

 plate is very large. 



1.3. The limited basal plate has a bony basi-branchial centre. 



14. The posterior lobes of the basal plate are very large, and ossified as a second 

 pair of hypo-brancliials, 



Seventh Family. " Pelobatid^." 



Genus Pelohates. 



34. Pelohates ftiscus. — Adult male ; 2 inches 5 lines long. Europe. 



In these types extremes meet under an apparent external harmony. Beneath 

 similar Taxonomic characters there are hidden the greatest contrasts in these two 

 European representatives of two of the lowest Families of Frogs. 



T 2 



