240 MR. W. K. PARKER ON THE STRUCTURE AND 



closest to the Neotropical Toads, with ornate skulls, but lie down below them, being 

 more generalised, and they are evidently abortively developed. 



These skulls form a great contrast to the Ranine "norma ;" the main differences are 

 as follows: — 



1. The skull is below the average size, bears no teetli, and its ossification is 

 excessive, and generalised. 



2. There is much asymmetry in both the suspensoria, and the investing bones. 



3. These latter are in several cases anchylosed to the endocranium ; and in two 

 species the palatines and vomers also. 



4. The snout is very wide, and has a generalised rostrum. 



5. The lower jaw is liinged to the head in front of the hmd skull. 



6. The tympano-Eustachian cleft is merely a small blind slit. 



7. There is no "columella" nor "annulus," in two out of the three kinds, and in 

 the third they are very small and arrested. 



8. There are no septo-maxillaries, and the maxillaries either only touch the very 

 small quadrato-jugal, or run short of it by a considerable space — as in the Aglossa. 



9. The basal plate is very long and narrow, and has no hinder lateral lobes. 



10. The left maxillary and nasal are less than the right (and sometimes the right 

 nasal is the larger bone), and the parasphenoid is less than half the length of the skull. 



Altogether, these may be said to lie at the very outside of their own sub-division, 

 from the higher types of which they differ almost as much as the Aglossa ; their place 

 is between the ornate Toads and Hijlaplesia. 



Fifth Family. " Engvstomid^e." 

 Ear rather imperfect ; sacral apophyses dilated ; toes free ; no parotoids. 



Genus Eruji/s^toma. 

 71. Engystoma carolinense. — Adult male ; 11 lines long. Florida. 



This is another very instructive instance of a small arrested skull (Plate 43, 

 figs. 7, 8), the length and greatest breadth of which are equal, and of the hinge of the 

 jaw being in front of the foramen ovale (V). Here the face forms a triangle, truncated 

 in front, the moderately broad snout being transverse. This form makes the relative 

 size of the hind skidl veiy large, and yet the j^arotic processes are small ; the occipital 

 ring, and the auditory capsides are unusually wide — more than in the newly meta- 

 morphosed young of typical kinds. The occipital condyles {oc.v.) are large and 

 posterior, they are separated by a space one half larger than their own lii-eadth. The 

 synchondrosis is rather wide, above and below, and there is an endosteal rudiment of 

 both basi- and supraoccipital {h.o., s.o.). 



