DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 121 



margin is cut away, but more irregularly, int(j four hIuiHow enuirginations. Tlie ribbed 

 orbital edges are higher than the middle, so that the top of the skull is gently con- 

 cave ; behind the superorbital edge there is a temporal notch. In front, these bones 

 scarcely cover in the fontanelle ; behind, they almost reach the foramen magnum. 



The nasals (figs. 5 and 7, n.) are curious stalked shells of bone ; the stalk is thick 

 and is pointed below, the dilated part fits on to the convex cartilage, does not come 

 near its fellow, and has a strongly crenate margin ; much of the middle and all the 

 fore part of the cartilaginous roof is exposed. 



In this very " Phryniscine " skull (see Plate 41) the prsemaxillaries are thrown 

 beneath the prenasal rosti'um (Plate 23, figs. 5-7, px.) ; they extend outwards a good 

 way, but are narrow, have a small palatine process, and an average nasal process. As 

 with the dentary below, so with the premaxillary, above, the bone is grafted on to a 

 labial cartilage, which cartilage it largely ossifies ; in this case it is the " inner upper 

 labial" (u.lK). All the cartilages of the outer nostril are large and solid — we shall see 

 the like again in the " Pelodryadidse " — and whilst above the opening (e.u.) the nasal 

 roof (al.n.) is very thick and crescentic, the front of the nostril is guarded by the large 

 "outer upper labial" (fig. 7, ii.P.), which is pedunculate and tridentate. 



The maxillaries {mx.) are long, narrow bones ; the jugal process reaches far back ; 

 and the quadrato-jugals (qj.), which are half as high as the maxillaries, are rather 

 long : they are extensively fused with the quadrate (q.). The real height of the 

 oblique backwardly -turned squamosal (sq.) is equal to half the length of the skull. 

 Its supratemporal part (fig. 5) is extensively developed over the auditory capsule, as 

 well as over the marginal " tegmen ;" the bone is cleft, as it were, to bind fore and aft 

 upon the parotic mass. 



The postorbital process (figs. 5 and 7) is falcate ; the edge of the temporal part 

 forms a crescentic porch to the ear, and the descending stem is a narrowish lath of 

 bone binding on the retreating suspensorium. 



The parasphenoid (fig. 6, ^J((.,s\) is large, well-developed, and Rcmine ; its short 

 " handle " is split, its basi-temporal " guard " is strongly sutured to the pterygoid 

 (where it lies over the pedicle), and the pointed "blade" reaches as far as to the wings 

 of the ethmoid ; the trough of the bone is deep (fig. 7, pa.s.). The vomers (fig. G, v.) 

 are remai-kable ; they are thick, and bent like "knee-timbers," are wide apart, have a 

 solid boss for the teeth, an out-turned front lobe which reaches the pre-maxillary angle, 

 and a round notch for the internal nostril {in.), which pfxssage is guarded by a long 

 spike of bone on the outside. 



As compared with the skuU of the typical species, this is very abnormal ; its most 

 important modifications ai-e : — 



1. The extreme flatness of the skull. 



2. The great extension outwards of the parotic wings. 



3. The extremely backward position of the quadrate articular condyles. 



4. The fusion above of the occipito-auditory bones. 

 MUCCCLXXXI. i; 



