DEVELOPMENT OP THE SKULL IN THE BATRACHIA. 219 



3. In the curious porcine form of the snout, broad and overhanging the facial bones. 



4. In having no teeth, either marginal or submarginal. 



5. In the fixity of the pedicle. 



6. In the breaking up of the palato-suspensorial cartilage. 



7. In the fixity of the stylo-hyal and the supra-stapedial, and in distinctness of the 

 stapedial " boss." 



8. In the narrowness of the basal plate, and the absence of hypo-hyal lobes. 



9. In having a second pre-orhital besides the septo-maxillary. 



Second genus. Otilophus. 

 63. (A) Otilophus margaritifer. — Half-grov/n female ; H inch long. Venezuela. 



This skull is about one-fourth less than the last ; it resembles it veiy much, but is 

 feebly ossified (at present), has a wider roof, and more ornate arid crested bones, 

 externally. If this skull had been arrested at this stage there would have been no 

 reason for the sub-generic distinction Otilophus, as distinct from Bufo. I agree with 

 that distinction, but would put B. ornatus into the sub-genus. 



We have here the same triangular broad roof, and high skull (Plate 37, figs. 5-7), 

 as in the last, but the occipital region projects more, behind, and the snout is much 

 narrower, and more rounded ; moreover the investing bones are very ornate with 

 small beads or pearls of clear bone. The figures (Plate 37, figs. 1-4 and 5-10) wUl 

 give a clearer idea of the great likeness and small unlikeness of these two exquisite 

 little skulls. The occipital condyles (occ.) are large, reniform, and postero-inferior ; 

 they are separated by a rounded notch half their own width, and they show, more than 

 those of the last kind, that the motions of the head on the atlas are very free, and 

 worked by strong muscles. 



The ex-occipitals (e.o.) are less than half the size of their region ; and both above 

 and below are separated by wide tracts of cartilage. The floor of the vestibule 

 (fig. 6, vh.) is naked cartilage ; the top of the ear-sac is all covered, except the epiotic 

 region (ep.), so that the prootics are only seen where they surround the foramina 

 ovalia (V.). The prootic region is wide, imossified, and forms a lai-ge tegmen {t.ty.) 

 under the squamosals (sq.). The large optic fenestras (II.) are surrounded by carti- 

 lage which occupies two-thirds of the orbital region (o.s.) ; this part is of almost equal 

 width, but widens at both ends ; its depth is very small (fig. 7), but it bulges in the 

 middle. The limited gu-dle-bone (eth.) is complete below (fig. G), and takes up its 

 own proper caililage ; above (fig. 5), it only appears just where the roof-bones partly 

 expose it as a circle of bone reaching the septum nasi in front, and the fbntanelle 

 behind, but it has much cartilage on each side. The main fontaneUe is rather small, 

 and elegantly heart-shaped ; the secondary fontanelles are large and oval ; the 

 " tegmen cranii " is largely developed and the endocranium is rather massive. 



The narrower and more rounded snout is extremely porcine ; the outer nostrils are 

 very large and not far apart ; the large round inner nares (fig. G, i.7i.) are twice as far 



2 1- 2 



