DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 
139 
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 Pelobcttes partly 
arises from the Bufonine stoutness of the latter, and the Hyline 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 Bombinator is underwrought; moreover, the former has a rudimentary 
columella, whilst Bombinator has none. 
Pelobates is as remarkable in showing ichthyic bony patches in the cerato-hyals as 
Bombinator in the basi- and hypo-branchials. Bombinator, in its skull, looks a little 
towards Dactylethra —that is, in the condition of the nasal capsules ; and it is, for the 
most part, like a young typical Frog. 
Its divergence from the last-mentioned species, or the type, 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 supero- posterior, 
4. The nasal capsules are almost entirely 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” articulare besides the outer plate. 
12. The cerato-hyal is greatly dilated distally, and the notch in front of the basal 
plate is very large. 
13. 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-branchials. 
Seventh Family. “ Pelobathle.” 
Genus Pelobates. 
34. Pelobates fit sens. —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 
