238 MR. W. K. PARKER ON THE STRUCTURE AND 



The foramen magnum (Plate 40, fig. G, f.m.) is large and obliquely superior; the 

 occipital condyles {oc.c.) are large and posterior. Measured along the axis, the orbital 

 region is longest, the nasal next, and the auditory the shortest ; this part, however, 

 is very wide, and the inner canals are very large and prominent; the posterior {p.s.c.) 

 has, over it, a spiny epiotic prominence (fig. 8, ep.). There is a narrow synchondrosis 

 both above and below, dividing the continuous lateral bony tracts {pr.o., e.o.). 



The large, square parotic tracts ai-e unossified at the tegminal edge {t.ty.), and this 

 is barely covered by the squamosal {sq.). There is a large cordiform, and two smaller, 

 oval, fontanelles and the dividing tracts are unossified over the middle part, the bone 

 retreating, laterally, in the prootic region. The lateral roof-edge of the endocranium is 

 moderately wide, and the main fontanelle is nearly covered by the roof bones (f-p.). 



The prootic encloses the preauditory nerves (III., V.) up to the moderate optic 

 fenestra (II.) ; tliere the cartilage (o.s.) is as extensive as the orbital part of the girdle- 

 bone (ei/t.) ; that bone, liowever, runs far into the true nasal region, ossif}dng two-thirds 

 of it ; the broad overhanging snout is unossified in its front third. The girdle-bone runs 

 well into its own wings, but it ]i;is not become anchylosed either with the palatines 

 or vomers (fig. 7, jja., v.), as it does in the other species. The outer nostrils (e.n.) are 

 very wide apart, the inner (i.u.) are scarcely more so, the whole fore face being so very 

 broad. The outer angles of the largely ossified subnasal laminae (fig. 7) are but little 

 more projecting than theii* general margin ; the pro-rhinals (ji.rh.) are slender and 

 uncinate. 



As in the other species, the ethmo-palatine cartilage is rounded ofi" in front, so that 

 there is bvit little pre-palatine ; the cartilage is much diminished in size, but it can be 

 seen outside the palatines and pterygoids (fig. 7, pt.pa., 2M-, p'J-), where they meet, 

 and it becomes large as it approaches the pedicle and quadrate (fig. 8). 



The two bony bars {pa., pg.) have the average Bufonine development, the fii'st is 

 falcate, and the second is arcuate and forked ; it becomes very wide behind, but the 

 part covering the pedicle, and ossifying it, is short. The part inside the quadrate 

 reaches no further backwards, for the hinge for the jaw {q.c.) goes scarcely further 

 back than the pedicle on the left side, but has retreated twice as far on the right ; this 

 arrest of the metamorphosis is a correlate of the unfinished form of the pre-palatine. 

 The condyles {q.c) are large, reniform, and oblique, the left is least transverse of the 

 two. The height of the suspensorium (fig. 8) is great, although it forms but httle 

 more than a right angle, in front, with the axis of the skull. The y<\xi of the ptery- 

 goid which passes inside the quadrate is pressed against the inner fork, and here there 

 is a small crescentic aperture (bhnd), with its convexity inwards — a rudiment of the 

 Eustachian passage (eu.). 



There is, as in P. varms, neither annulus nor columella; the stapes (figs. 7, 8, st.) is 

 very large, oval, hollow, umbonate, and unossiiied. The stylo-hyal end of the hyoid 

 [st.h.) is confluent, the whole bar (fig. 9, c.hy.) is narrow, and here is what I failed to 

 find in the other two kinds, viz. : a projecting corner to the hj'po-hyal. The notch 



