DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 183 



and below, along a third, of the projaer nasal territory. This extensive bony tract takes 

 in the ethmoidal wings up to the proper _/aaaZ ethmo-palatine {e.jia.), and uses up the 

 small superorbital projections (s.oh.). 



The roof and floor of the nose have the usual width ; the latter nan-ows, crescentically 

 at the middle, and the i-oof is widest behind. The septum nasi (tig. 11, s.n.) is thick and 

 well marked, it ends in a distinct prenasal, to the sides of which are fused the horns 

 of the roof crescents (on each side of s.n.). As in Hyla Exoingii (see Plate 31, fio-s. 2 

 and 4, p.rh.), the pro-rhinals (fig. 12, behind j:)a3.) have the form and appearance of the 

 angles of the primary cornua, and are half as large— a very unusual size. The append- 

 ages of the nostrils {u.l\u.l'-.) are well developed ; these passages are at the average 

 distances, outside the crescentic snout; the inner nostrils («.«.) are large, circular, and 

 their distance is one-fourth greater than that of the outer holes. The palato-sus- 

 pensorials are in several respects varied from the norma ; the palatine portion is 

 evidently stronger than the pterygoid, and the arch is angulated where these regions 

 meet. The ethmo-palatine {e.pa.) narrows as usual where it joins the ethmoidal wing, 

 and both this lessening, and the cessation of the bony deposit, mark off the true facial 

 part. The pre-palatine is the point and edge of a dilated blade, and under this a 

 large palatine bone (^^f-) binds, which is falcate and dilated externally, and has a 

 cidtrate ridge growing from its middle tliird — like an old tooth-bearing crest ; as in 

 Bufo agiia, Callula pulchra, Cystignathus ocellatus, and some others. 



The pterygoid bone {pg.) is slender, but strong ; the re-entering angle of its fork is 

 rounded, its inner fork {pd.) forms a suture with the skull, and ties down the carti- 

 laginous pedicle, as in Hijla alhomarginata (see Plate 32, fig. 7). The quadrate region 

 is rather short, moderately retral, and considerably ossified ; the condyle {q.c.) is a well- 

 formed bi-cristate trochlea. There is a middle sized annulus {a.tij.) ; its band is wide, 

 leaving a small central space; it is open above. The mandible (fig. 13) is perfectly 

 typical, and the Eustachian opening (fig. 12) is oval and rather large. The stapes 

 (tig. 15, St.) is large, oval, and knobbed; the medio-stapedial {m.st.) is pistol-shaped, 

 with a heavy " handle" of cartilage, notched off" from the bony part, and itself emarginate 

 behind. The shaft is arcuate and very slender ; it is followed by an extra-stapedial 

 {e.st.) which is two-winged, and the wings are crenate. A bud gi-ows from the middle 

 of this oakleaf-shaped plate, which ends as a free knob, behind, but from which no 

 ray protrudes, as a supra-stapedial. 



The stylo-hyal (fig. 12, st.h.) is confluent above, and passes into a middle-sized tape 

 (fig. 14, c.luj.) that ends in a straight hypo-hyal horn {h.hy.). 



The retiring part passes quickly into the base, for the " notch " is shallo\v ; so also 

 the plate iiseiS {h.h.hr.) is of small extent, fore and aft, and has no front lobes, only long 

 hinder processes. The large, expanding, highly ossified thyro-hyals (t.hy.), diverge 

 considerably behind ; in front they are anchylosed together, and tliere they form 

 a " basi-branchial " bone (b.hr.), whose wedge-like point nearly reaches to the selvedge 

 of the emarginate basal plate. 



