DEVELOPMENT OP THE SKULL TN THE BATllACHIA. 35 



The antorbital pedicle (" etlimo-paktine ") {e.ixi.) is now a flat tape, narrowest in 

 the middle; the "post-palatine" (pt.pa.) is a similar tape passing insensibly into the 

 still narrower "pterygoid" (pg.), which latter passes into the siispensorium where it 

 subdivides into its three forks. 



The lowest part ends in the reniform quadrate condyle (q.) ; and the position of the 

 hinge is opposite the prooticand the foramen ovale {pr.o., V.), instead of being in its old 

 place opposite the front of the nasal capsules. 



This is, truly, only part of the way back of the condyle (see in the adult Bana pipiens, 

 Plate 8, where it gets some distance behind the occipital condyle), but this is a good 

 distance to be travelled whilst the legs have been growing and emerging, and the 

 lungs gradually rendering the gills unnecessary. 



The spiracular cartilage (sp.c.) has begun to take on its crescentic form, and is now 

 an evident annulus tympanicu.'i. The epi-hyal has not yet appeared, ready to become 

 the columella; the cerato-hyals (fig. 10, c.hy.) are dislocated from the suspensorium, 

 the hinge having become absorbed ; they lie behind the first pair of clefts, which, of 

 course, are between them (on each side) and the corresponding suspensorium. 



This latter part, the mandibular " pier," has lost all its dorsal end, the nan'ow 

 upper tract of the " pedicle " having been completely absorbed. The stunted, ampu- 

 tated part has now a flat condyle on its end, which glides on the facet formed for 

 it over the front of the ear-capsule below. 



Above, the " otic process " (or third part) of the suspensorium (ot.p.) has crept close 

 to the fore edge of the tegmen tympani, ready for fusion ; it is already invested with 

 the squamosal {sq.), which lies in front of a gentle ridge — all that remains (now) of the 

 " orbitar process." The arches, pouches, sub-basal and basal plates of the branchial 

 cartilages are reduced to a lozenge-shaped plate, ending in a pair of diverging rods, 

 and ready to unite, in front, with the attenuating cerato-hyals (fig. 10, c.h>j., 

 b.h.hr., t.hy.). 



I shall next describe the condition of the skull in young Frogs, when that which 

 was left unfinished in the cranium, on their assumption of terrestrial life, will be seen 

 to have gone on unto perfection ; and the " headstone " brought on to this graceful 

 piece of vegetative architecture. 



Skulls of Young and Adult "Ranid^." 



Seventh Stage J^' — 4. Skidl of Rana palustris {Cambridge, Mass., U.S.). Young 

 recently metamorphosed ; 11 lines long. 



The figures of this (Plate 5, figs. 6-10) and the next (figs. 1-5) stages show the endo- 

 cranium with the outer bony laminae removed from one side, and retained on the other ; 

 and these, whether they are bones that are permanently, or only for a time, distinct. 



• If the three early stages of the larval .skull (in Bufo vulgaris) were added to these, this wouUl be the 

 Tenth Singe, 



F 2 



