DEVELOPMENT OF T]IE SKULL IN THE BATRACHIA. 259 



Certainly, in many of the Anura, more or less cartilage appears in the outer edge ot 

 the hyoid bar, but quite distinct from it, corresponding exactly to the basal part ot 

 the pectinated inter-bi-anchials of the hyoid bar in the Shark and Chimcera. 



The hyoid bars, the soft basi-hyal, the rudimentary cerato-branchiuls, the paired 

 hypo-branchials, and the median basi-branchial all fuse together to become the hyo- 

 branchial apparatus of the adult. The narrowed and ossified hypo-branchials are true 

 " thyrohyals," like those of the Manimal 



Among the newly appearing parts are the stapes {early), and the columella {late). 

 The stapes appears about the time of the first bony tracts; but the columella, as a rule, 

 not until some months after metamorphosis. It appears whilst the tail is still large in 

 Pseudis; and long before hatching in Pipa; in Dactyletkra it is as late as in the 

 ordinary " Phaneroglossa." 



E. — Tlie normal {or Ranine) adult skull compared with sub-typical and aberrant forms 

 in the " Anura," generally, where larval structures are in some degree retained, or 

 cohere generalised {ichthyic) cJiaracters turn up; lastly, the residuum of characters 

 which are universal. 



The prootics (or spheno-prootics) and ex-occipitals are not separately ossified, as 

 in the " norma," in Psetidis, Dactylethra, and others. In some kinds, as Acns, Pseudo- 

 phryne, Diplopelma, there is a small basioccipital ; in some of these small kinds there 

 is an evident endosteal super-occipital. 



The girdle-bone is absent in some dwarf kinds, as in some small West African Pance, 

 in Gomphobates, and in some species of Diplopelma. 



The girdle- bone is in two pieces in Diplopelma ornatum, in Engystoma, and in 

 Pseudophryne ; there is a large f'shaped, persistent membrane bone over the eth- 

 moidal region in Dactylethra, a crescentic bar in Rappia bicolor, and a similar bone, 

 not persistent, in Rami temporaria. 



As a rule, there are two lesser fontanelles over the hind skull besides the main 

 space, but in many kinds there is only the large one ; in Alytes there is one lesser, 

 hinder fontanelle. 



In some of the Frogs {Rana, sp.), still better in the HyUdee, there is a superorbital 

 "eave" of cartilage; in Phyllomedvsa bicolor, llyla rubra, &d6. especially in Alytes 

 obstetricans, tiiere is a separate superorbital cartilage, besides. 



The nasal region is often largely ossified from the girdle-bone ; this tract may be a 

 true " sphenethmoid," as in Dactylethra, where it does not finish the ethmoidal region 

 in front, but runs back to the auditory capsules. 



The nasal roofs ai-e only partially covered by their own proper cartilage in the genus 

 Bifo, in Dactylethra, and in some others ; the pro-rhinals are distinct in Rana esculenta 

 and in Dactylethra ; the two nasal fenestroe of Pufo answer to the series of shts in 

 Alyxine. 



In Bufo vulgaris and some other species of that genus (not in B. calamita) the 



