DEVKLOPMKNT OF THE SKtlLL TN THE BATRACHIA. 231 



on each side; these are the Literal rudiments of the girdle-bone {eth). These cochleate 

 tracts reach the top of the cranial wall for a small extent, and also run into the 

 ethmoidal alje, but they are far apart, above and below. These are the true " lateral 

 ethmoids," but between them the " perpendicular plate " is in rudiment ; this is a 

 triangular tract of imperfect bone at the middle of the floor, just over the front 

 of the parasphenoid (fig. 2, pa.s.). The fore part (tf the chondrocranium is well 

 developed, but quite unossilied ; the subnasal laminae {s.n.l.) are broad, with large 

 falcate angles, and well formed pro-rhinals (p.rh.); the roof {>i.r.) is well developed, and 

 has a distinct ring of cartilage round the oi;ter nostril [eji., n.iv.); these passages are 

 at a moderate distance, and are well protected by the labials {u.P.u.I'-.). The palato- 

 suspensorials are largely developed in front, for the ethmo-palatine bar (fig. 2) expands 

 into a large adze-shaped plate, the pre-palatine part of which (fig. 4, e.pa., pr.pa.) 

 almost reaches the angle of the nasal floor. There is just a thread of bone answering 

 to the palatine ectostosis (figs. 2 and 4, pa.). 



The partially retreated hinder jaai't of this arch is still continuous with the basis 

 cranii by the unabsorbed pedicle {pd.) ; the joint-cavity is there, but is not complete — 

 as in the species of Bufo and other types, where the strong pterygoid binds this part 

 down. Here, however, that is not the cause of the unfinish of the joint, for this bone 

 {pg.) is very feeble as in young Toads and Frogs. 



The condyle of the quadrate {q.c.) is a large bilobate trochlea; the body of the 

 suspensorium (fig. 6, sp.) is not ossified. There is a small ligulate sub-crescentic 

 "annulus tympanicus" (figs. 5 and 6, a.ty.), but no columellii. 



The stapes (figs. 5, 6, st.) is large, oval, and apiculate, behind; the stylo-hyal {st.h.) 

 is loosely attached to the capsule. 



The rest of the baud is wider (fig. 3, f.hy.) and is definitely dilated before it turns 

 back as the hypo-hyal {h.hi/.). 



The notch in front of the basal plate (b.h.hr.) is shallow, the plate itself short, the 

 fore side lobes large and stalked, the hind side lobes very short, and the thyro-hyals 

 {t.hij.) large and moderately divergent. 



The mandibles (fig. 3) are quite normal, but the ossified labials {in.mh) are very 

 large, and so are the articular condyles {ar.c.) ; the articular bone {(ir.) rises directly in 

 front of the condyles, l)ut very little in the coronoid region; the dentary ((/.) is small 

 and feeble, and the rod of cartilage {mk.) is not much affected by the bone, outside. 



The investing bones are all in a quasi-juvenile condition ; the fronto-parietals {/.p.) 

 remain distuict, right and left; they more than cover the large fontanelle, and overlap 

 the auditory capsules and su})er-occi[)itals moderately. 



The nasals («.) are thin shells of bone, imperfectly covering their own region ; the 

 premaxillaries, maxiUaries, qiiadrato-jugals, and squamosals (j:>a:., mx., q.j., sq.) have 

 all the same feeble arrested character. 



So, also, the parasphenoid ( pa.s.) ; it has all its processes but is only two-fiflhs the 

 length of the skull, and is less developed than that of the Tadpoles of many kinds. 



