362 PROFESSOR OWEN ON THE GENUS PALAPTERYX. 



The basisphenoidal platform (a, fig. 3) has a small perforation at its middle : the 

 anterior angles are formed by the short thick outstanding pterygoid processes (s'), with 

 flat oblique articular surfaces for the abutment of the true pterygoids. 



The presphenoidal rostrum (9, broken away here) is continued straight from the fore- 

 part of the platform, of which no transverse ridge defines, as in Dinornis, the anterior 

 limits. The alisphenoid (6, fig. 1) forms, as usual, the anterior irregular wall of the 

 tympanic cavity, is perforated by the foramen ovale [tr, fig. 3), and ascends to meet the 

 parietal in the temporal fossa. The parietals (7, figs. 1 & 2) are very broad and flat ; 

 more feebly impressed by transverse grooves than in Dinornis. The base of the mastoid 

 (8) stands well out, and the three-sided pointed process descends vertically from a ridge 

 which crosses its base, and which bends down at a right angle upon the fore-part of the 

 mastoid (s, fig. 1). The inner side of the process is excavated by the outer and fore- 

 part of the tympanic articular cavity {y, fig. 3). A smooth tract, three fines broad, of 

 the upper surface of the cranium divides the occipital (3, 4) from the temporal fossa 

 (6, fig. 2), as in the large Palapteryx strutho'ides (pi. 38. fig. 3). Two very slight con- 

 vexities on the frontals indicate the cerebral hemispheres. The postfrontals (12) arch 

 downwards, are slightly impressed behind their base by the temporal fossae, are more 

 slender in proportion to their length than in the cranium of the Palapteryx figured in 

 PL LV. fig. 4, 12, and have a short groove on the under side of their base : they terminate 

 freely at a distance from the mastoids (s). 



The frontals (PI. LIV. 11, 11) are continued further forwards than in Dinornis, to form, 

 with the prefrontals with which they coalesce, the roof of the capacious olfactory chambers 

 (18, 18, fig. 3). The antorbital processes (fig. I, a) bend down, and are longer and more 

 slender than in Dinornis : they are impressed beneath by a smooth articular surface for the 

 lachrymals. The anterior border of the frontals between these two processes, where it has 

 coalesced with the nasal and nasal plate of the premaxillary, forms a plate of bone above, 

 and is distinctly traceable from the coalesced prefrontals, though these are in contact 

 with the overarching plate and not separated from it as in the Dinornis. Feeble depres- 

 sions indicate the form and extent of the nasals and premaxillaries that are confluent 

 with the frontal ; but the broken edge is thinner as well as narrower, indicative of a less 

 powerful bill than in Dinornis. 



The median coalesced vertical plates of the prefrontals have been absorbed or unossified 

 at the middle line or septum of the cranial olfactory chambers : but they expand above 

 into broad plates (h, figs. 1 & 3) overarching those chambers. These together form an 

 ovate cavity (is, is) at the under and fore-part of the cranium, partially divided trans- 

 versely and with the great end or division anterior, one inch four lines in length and 

 eleven lines in greatest breadth. Each olfactory nerve appears to have entered its 

 compartment of the cavity by one large and several small foramina, which pierce the 

 hind and upper wall, and leave fine radiating grooves there. There are traces of the 

 same foramina and radiating grooves in the other crania of Palapteryx, but the large 



