226 MR. W. K. PARKER 0^ THE STRUCTURE AND 



(p-n.) is more definite than in that type. The occipital ring projects less ; the condyles 

 are separated by their own width only, and they are large and not posterior, but 

 postero-inferior. The synchondroses above and below {s.o., h.o.) are equal in both, 

 and have an endosteal deposit. The roof is less wide behind, shows only the large 

 fontanelle, and the tegminal growth is altogether less, so that the fontanelle takes 

 up more than three-fourths of the roof The sides of the occipital ring and the 

 auditory capsules, with then- convex canals, are all continuous in their bony invest- 

 ment, right and left {e.o., to V.) ; and there is the same small headland unossified 

 at the veiy limited tegminal edge (t.ty.). There is cartilage also where the pedicle 

 fits on, and where the stylo-hyal unites beneath, with the skull {pel., st.h.) ; also in 

 front, below, the large optic fenestra (II.) is surrounded by cartilage, and the foramen 

 ovale (V.) by bone. 



The gradually narrowing orbital region is more overlapped by the roof-bones (fig. 9, 

 /■J).), and three-fifths of the wall is unossified, and nearly all the floor. The lateral 

 rudiments of the girdle-bone (eth.) are less, and run into their own alee partially ; yet 

 an endosteal deposit, mth scarcely any perichondrial bone (ectosteal palatine), runs 

 up to the cheek. These ethmoidal wall-bones reach the roof externally (fig. S), but are 

 separated by their own width below (fig. 9). Here we have a much more perfect 

 median bone than in Pseudophryne (Plate 42, fig. 2), for the intertrabecular bar 

 is ossified for the fore half of its extent. In front, the base of the septum nasi [s.n.) 

 is ossified almost up to the rostrum {p.n.), and between the lateral ethmoidal centres 

 (eth) the bony deposit is continued for some distance in two tracts (p.e.). Here we 

 have the continuous " mesethmoid " of the Ostrich Family foreshadowed, in which the 

 bony deposit also takes place right and left of the cartilaginous wall. 



The unossified roof and floor (below «., and above sji.l.) are moderately wide ; the pro- 

 rhinals (fig. d,2).rh.) are small and sharp ; the prenasal (jf-n.) is rather large, the front is 

 sinuously transverse and of medium width, and the sub-tubular nostrils are defended 

 by well-developed valves (u.l^.u.P.). The ethmo-palatine (e.jKi.) is slender, and the 

 external part adze-shaped ; the bone (fig. 9, a) is mainly endosteal, and the post-palatine 

 tract is either separated from the pterygoid cartilage, or united by a very fine thread. 

 The pterygoid (pr/.) is typical, and partly ossifies a free pedicle (jJf/.). The quadrate 

 is unossified ; the condyles (q.c.) reniform and oblique ; and the Eustachian openings 

 (eu.) are only half the average size. The same may be said of the annulus {a.ti/.), 

 whose horns are not united. 



The stapes (figs. 9 and 10, st.) is not so lai'ge as in Pseudopjhryne, and only 

 half as convex ; its margin is cartilaginous, the rest is thin bone ; its oval form is 

 modified by a slight emargination before and behind. The columella (fig. 10) is almost 

 of the average size ; the whole rod is continuous ; there is a semi-osseous enlarge- 

 ment of the medio-stapedial (in.st., i.st.) behind, but no joint, and the bone is arched 

 and geniculate; the extra-stapedial [est.) is a small oval shield, with a free supra- 

 stapedial spike. 



