19G MR. AV. K. PARKER ON THE STRUCTURE AND 



1'lie palatines (Kg. 8, pa.) are wide apai't, are sub-falcate, and have a dilated outer 

 end, which is notched in front. The pterygoid {pg-) fails, by a third of the length of 

 the juguna, to reach the palatine ; it clamps the under side and inner edge of the 

 cartilage, arches suddenly ivjund to bind on the pedicle, and turns inwards to bind 

 the quadrate, making an elegant sigmoid curve. The pedicle, as in Pelodrijas, is very 

 large, and its thick condyle is obliquely external to the ear-mass, with which it 

 articulates. 



The almost transverse direction of the arch at this part, and the inbinding of the 

 quadrate, also contracts the space for the Eustachian passage. The stylo-hj'al (st.h.) 

 has coalesced, contrary to rule, with the outer angle of the condyle of the pedicle (fig. 8, 

 cpcl.), and arising as a hook bent forwards, this boundary bar also helps to lessen the 

 passage, which is crescentic, with its convex margin looking forwards and outwards. 



Here, owing to the depth of the retreating quadrate, the pier of the mandible — 

 after the absorption of its dorsal end, half-way across the wide postorbital region — 

 is still equal in length to its pterygoid outgrowth (fig. 9, pg.y q.). Above the reniform 

 condyle {q.c), which is less than in the last kind, there is a considerable tract of bone. 



The annulus {a.ti/.) is more than equal in size to that of Pelodri/as, and its fore horn 

 is better developed, for it has formed a lobe above which almost touches the lesser 

 horn ; the front of the tegmen, clamped by the squamosal {t.t>/., sq.), being thrust out- 

 wards, has made the position of the annulus very obhque (fig. 9). 



The epi-hyal element (figs. 9 and 10), although specialised for a new function, is well- 

 nigh as long, relatively, as in the Teleostei, and much longer than in the Rays. Looking 

 at it from a simply morphological point of view, we see in it both the pharyngo-hyal of 

 the Chimtera, as well as the e2n-hyal proper, and also the segmented "symplectic" of 

 the Sturgeon and the Paddle-fish. The top of this three-jointed epi-hyal fits into a 

 most remarkable periotic piece — the stapes {i^t.). This part of the paraneural pouch 

 is sub-quadrate, bilobate behind, and cupped, antero-externaUy, with a thick crescentic 

 half-rim to the hollowed part. 



The semi-osseous iuter-stapedial (i.st.) is bulbous above to fit into this hollow, and 

 then narrows to articulate with the slender terete sub-arcuate medio-stapedial (w.A'f.), 

 which has its distal end soft. That unossified knob is nearly cut off from the extra- 

 stapedial or " symplectic" {e.st.) by a segmenting notch. This distal part is compressed 

 into a high supra-stapedial angle which gives rise to a mere ligament {s.tit.) ; then the 

 bar flattens in the other direction to form the normal spatulate manubrium. 



Here the apex of the lower element of the hyoid arch (stylo-hy.'d) has coalesced, 

 not, as usual, with the floor of the tymjianum, but with tlie stunted apex of the 

 upper element (pedicle) of the arch next in front of it ; a very rare state of things.* 



* In my earlier researches into the development of the Batraehian skull ("Fiog-'s Skull," Phil. Trans. 

 1871, Plate 7, fig. 4, sy.), I supposed that part of the hyoid to have become confluent with the mandibulai- 

 pier; that this never takes place in the Common Frog, Professor Huxley showed me, and I soon found 

 the truth of the matter. Here, however, is an instance of this sort of thing, and in the larger and lower 



