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



tliere is a small bony basi-brancliial {h.hr\). The thyro-hyals {t.hij.) are normal, tbey 

 are long, straight, and moderately divergent. 



Tlie mandible (fig. 9) is normal, but there is some endosteal deposit in the hinge. 



The investing bones are very thin, but are dense, smooth lamince; the fronto-parietals 

 if-l^-) '^^® separate ; the two form a roughly pentagonal tract, they cover the hind skull 

 largely, partly overlapping the canals, and well overlie the wide roof'-.space ; their nasal 

 suture is nearly transverse. The nasals (n.) are broad elegant shells of bone, showing 

 the vascular rete through their thin clear substance; they meet along the middle, 

 and send a curved horn over the sub-tubidar nasal passage, in front, and another 

 downwards, behind, to join the maxillary. 



The preraaxillaries, maxillaries, and quadrato-jugals (p,r., mx,, q.j.), are narrow, and, 

 relatively, feeble bones ; the squamosal {sq.) is very small, has an uncinate postorbiLd 

 process, and binds merely on the anterior part of the small tegmen tympani {t.tij.). 



The only other Batrachian known to me with a parasphenoid equal to this is Pipa ; 

 it is more like that of the " Urodeles " (Phil. Trans., 1877, Plates 24-2G). It stretches 

 from near the foramen magnum, to opposite the ethmoidal axillae, and the width is 

 such as nearly to roach the foramina ovalia (V.) ; it then expands in lozenge-shaped 

 processes under the ear-capsides ; the narrowing of the fore part takes place gently, 

 and there the bone is like a (relatively) large spoon. The vomers (fig. 8, v.), on the 

 contrary, are mere crescentic films of bone, bounding the inner edge of the internal 

 nostrils {i.n.). 



As compared with the " nonna," this skull is — 



1. Very small and arrested, the face being feeble, and the cranial cavity very large, 

 relatively. 



2. There are endosteal rudiments of the keystone and threshold bones — basi- and 

 supraoccipitals. 



3. The bones of the hind skull are generalised, or continuous on the same side. 



4. The moieties of the girdle-bone are wide apart, and run into the palatine region, 

 ossifying the cartilage, and suppressing the normal bony plate. 



5. There is a distinct prenasal rostrum. 



G. The parts of the middle ear are only feebly developed, and the stapes is a hollow 

 semi-osseous shell. 



7. The hyo-branchial apparatus is solid at its attachment, has an extra-hyal 

 cartilage, is sub-crescentic, and possesses a distinct basi-branchial bone. 



8. The roof- and floor-bones are very wide, the marginal bones narrow, and the 

 vomers extremely minute ; there are no septo-maxillaries. 



