PROFESSOR OWEN ON THE GENUS NOTORNIS. 367 



platform ; the posterior angles are hemispheric tubercles (i") as in Palapteryx. The pre- 

 condyloid holes {p, fig. 10) are nearer the carotid holes (c, fig. 9) than in Palapteryx, 

 opening into the upper part of the same fossa. The occipital region incUnes forwards 

 as it rises, and is defined above and laterally by a strongly marked ridge (2,3, fig. 10), 

 which forms a slight angle above the base of the mastoid : the occipital surface is not 

 divided by a median vertical ridge. In Porphyrio (figs. 1 & 4) the plane of the occipital 

 foramen inclines from below upwards and backwards ; that of the occipital surface is 

 vertical ; it is proportionally narrower than in Notornis. 



The mastoid (s) gives off" a short compressed angular tympanic plate (s, fig. 8). 

 The fractured base (s', fig. 9) of a process answering to that of the true mastoid process 

 in other birds, and marked a' in the skull of the Dinornis (PI. LII. fig. 1), comes off 

 from the lower part of the temporal fossa more in advance of the process s, and rather, 

 as it would seem, from the alisphenoid than the true mastoid. The same pecuUarity 

 is repeated in the cranium of the Porphyrio (PL LVI. fig. 1, s'). The articular surface 

 for the tympanic is divided, as in Dinornis proper, into two subcircuiar cavities 

 (y, y', fig. 9) by a pneumatic foramen. The parietal region (7, fig. 8) is singularly flat : 

 the temporal fossce (between s and 12) unusually long ; well-defined by the ridge extend- 

 ing from the paroccipital to the postfrontal : this process (fig. 7, 12) is short, obtuse, 

 directed downwards and backwards ; broader in Notornis than in Porphyrio. The 

 temporal fossa is equably divided by an intermuscular ridge (8', fig. 7) probably con- 

 tinued upon a mastoid process as in Porphyrio (fig. 1, 8'). The whole inferior border 

 of the temporal fossa is produced as a vertical ridge below the level of the adjoining 

 basis cranii in both Notornis and Porphyrio, which gives a very peculiar character to 

 this part of the cranium. This ridge (fig. 9, s') bounds the outer side of a large and 

 well-defined muscular impression with intermuscular ridges extending from the anterior 

 tympanic articulation (y) to the fore-part of the base of the postfrontal (12). There is a 

 similar muscular depression in the Porphyrio : in the Maccaw it is much shorter, by 

 reason of the less antero-posterior extent of the temporal fossa. The fore-part of the 

 frontal, which extends beyond the cerebral cavity, and appears to have anchylosed with 

 the base of the upper beak, has been broken away, exposing a fine pneumatic diploe 

 (rf/, fig. 8), and the olfactory outlet {ol, fig. 11), which appears to have been common to 

 both nerves ; but there is no trace of olfactory chamber at this part, as in Palapteryx. 



The chief singularity of the cranium, so mutilated, but with the cerebral cavity 

 entire, is its regular four-sided figure ; the breadth of the fractured anterior part being 

 almost that of the occipital region, and the extent of the sides being scarcely more than 

 that of the front and back part. This character is very striking as we look upon the 

 almost flat basis cranii (fig. 9), and is well-marked when the cranium is viewed from 

 above (fig. 8), where a smaller flat square platform (7, n) is defined by the occipital and 

 temporal ridges in the middle of the large square ; of which smaller square the anterior 

 boundary is wanting, the platform here sloping gradually down to the base of the bill. 



