iDEVELOPMENT OF THE SKULL IN THE BATRACHIA. 213 



6. Both supra-stapedial and stylo-hyal are confluent. 



7. The medio-stapedial is a very short bone and the inter-stapedial takes up most of 

 the rod. 



8. The extra-stapcdial is peltate. 



(51. Bufo calamita. — Adult female; 2| inches long. England. 



This skull (Plate 40, figs. 1-5) is, on the whole, about as strong as that of B. vul- 

 gans, but it differs greatly from it in several things, notably in having what is quite 

 exceptional in the genus, viz.: an open fontanelle (/o.). The length is to the greatest 

 breadth as 6 is to 7 ; the condyles for the lower jaw reach very little further back 

 than the condyles of the pedicles ; the outhne of the face is a very exact semi- 

 oval. There is in every part a remarkable Bufonine coarseness of structure, in spite 

 of the arrest of the roof bones : the ossification of the endocranium is normal, as in 

 B. vulgaris. 



The occipital condyles (Plate 40, figs. 1, 2, oc.c.) are large, postero-inferior, and sepa- 

 rated by a shallow notch less than half their own width. I can find no secondary 

 fontanelle ; the main space (fig. l,fo.) is oval, and is half the length, and more than 

 half the width of the roof, most of which is uncovered. The upper and lower synchon- 

 droses {f.m.) are wide, and widen rapidly so as to become large cruciform tracts 

 between the prootics and ex-occipitals {pr.o., e.o.). The latter merely form a flange 

 to the epiotic eminence, above {au.) ; below, they well enclose the double foramen 

 for the 9th and 10th nerves (IX., X.). 



The prootics reach to the facet for the pedicle, right and left, and to the optic 

 fenestra in front (fig. 2, IT.), quite enclosing the hole for the trigeminal (V.). 



Above (fig. 1, pr.o.), they reach far over the capsule, nearly up to the squamosal 

 (sq.), but the narrow tegmen tympani and the whole of the eminence over the pos- 

 terior canal are unossified ; they are confluent with the temporal wing of the roof- 

 bones {/■])■)■ The mid-skull narrows steadily up to the ethmoidal alie and axillre ; it is 

 half cartilage and half bone^ for the girdle-bone {eth.) has its normal development, 

 affecting the septum nasi a little, above, not quite reaching it below, and only partly 

 ossifying the also. The whole of the nasal territory is cartilaginous ; the floor is wide, 

 its angles in front are not large, yet the pro-rhinals (fig. 2, jj.?-/;.) are unusually large, 

 but straight, as in most Toads ; there is no prenasal rostrum. The roof (fig. 1, n.r.) is 

 very narrow, and I cannot find the band which, at a distance from the septiun, runs 

 back to the ethmo-palatine in most species o( Bufo ; here the true nasal '•paraneural" 

 cartilage is mainly confined to the fore part of the snout. The oblitpie external nostrils 

 (fig. 1, r.n.) are well defended by the second labial {u.P.); the first {u.l\) is a mere pad 

 inside the nasal pi-ocess of the premaxillary ; the internal nostrils («'.«.) are round, and 

 not much wider apart than the outer. 



The palato-suspensorial structures are large and strong, but the whole arch is 



