DEVELOPMENT OP THE SKULL IN THE BATRACHIA. 195 



the auditory capsules, is continuous bone. Above, the cartilage persists for a small 

 extent behind the fontanelle ; and, outside, the tegmen {t.tij.) is unossified. This soft 

 tract is less than half the huge jiarotic wing, which extends beyond the horizontal 

 canal (li.s.c). The three canals {ci.s.c, h.s.c, p.s.c.) are small, but well marked ; 

 beyond them the parotic projects as far again from the middle of the skull, and 

 increases in width so as to be equal in size to the hind skull. In this kind the 

 tegmen is rounded behind, and sends outwards, and downwards, a. projection in front, 

 like the process that appears, behind, in Pelodrijas. The whole outline of this two- 

 winged hind skull is strongly sinuous, behind and before. The fontanelle (/o.) is 

 heart-shaped, and is open over a third of the cavity of the skull ; it has a considerable 

 tegminal margin. The narrowing in front of the temporal region is followed by a 

 continual increase in width up to the superorbital cai'tilages ; and the skiUl (figs. 7-'.)) 

 is both wider and shallower than in Pdodi-yas. 



The prootic bony tract runs round the foramen ovale {pr.o., V.) up to the optic 

 fenestra (11.) ; this latter opening is very large, as in some of the lesser Australian 

 IlyUv. A definite margin of cartilage {o.s.) bounds that fenestra in front, and then 

 the girdle-bone {cth.) begins; it does reach the edge of the skull-wall, but does not 

 occupy the all proper ethmoidal territory either in front, or antero-laterally. Here, as 

 in Pelodryas, the ethmoidal region has two pairs of wings, the front pair confluent 

 with the nasal region, whilst the hind pair are the projecting superorbital eaves. 



Here we have, as in Alytes, a separate, but smaller, superorbital cartilage (.s.oi'.) ; 

 it is finger-shaped, and turns downwards (fig. 3). The outspread cranial roof runs 

 forwards into the nasal roof, and outwards on to the ethmo-palatine bars (e.pu.). Tlie 

 distance from the foramina ovalia (V.) to the front of the gii-dle-bone is equalled by the 

 cartilage in front of that bone. The trabecular floor (s.n.I.) is immense ; the nasal roof 

 is only a little smaller; but, from the narrowing of the snout, which is transverse, in 

 front, the outer nostrUs are only half as wide a^aart as the inner. These latter {i.v.) are 

 as large as the Eustachian openings of Pelodryas ; they are oval, and their direction is 

 inwards and forwards. The openings for the nasal nerves (inside s.n.I.) are large, f;xr 

 backwards, and wide apart, the floor is narrowed between them and the inner nostrils ; 

 it is definitely notched at its sudden narrowing. 



The pro-rhinals (;3.)'/i..) are well-developed, near together, and out-turned ; but the 

 angles of the nasal floor converge in a remarkable maimer in front ; they are bilobate 

 {c.tr., s.n.I.), and the hinder lobes diverge. The septum nasi (s.n.) is moderately thick, 

 and is rounded off in front, so that there is no definite rostrum. The nasal roof and 

 wall (fig. 9, (d.n.) are well developed, especially the latter, which is an unusually large, 

 wide, ear-shaped band. The labials [ii.I^.ii.l'-.) are normal, and are larger than in 

 Pelodryas. 



The palato-suspensorial arch di^•erges outwai'ds to the postorbital region ; it is of 

 great breadth throughout, and so are the bones applied to it ; these, however, do not 

 greatly affect the cartilaginous pith, which is nowhere obliterated. 



2 c 2 



