PROFESSOR OWEN ON THE GENUS DINORNIS. 311 



regard to its slope, as in the Argala and Ostrich .- the occiput in the Apteryx is nar- 

 rower, higher, almost vertical, with the middle part produced backwards into an angular 

 projection and perforated on each side : the upper region of the head is much more lofty 

 and convex than in the Dinornis ; the mastoid process is much smaller in proportion to 

 the par-occipital process : the temporal surfaces resemble those in the Dinornis in their 

 antero-posterior extent, but do not impress the sides of the cranium ; the orbits are much 

 smaller, and the olfactory cavities much larger in the Apteryx than in the Dinornis ; 

 but it is interesting to find the nearest approach to these peculiarities of the existing 

 Struthious bird of New Zealand made by the extinct StruthionidtB of the same island. 



The cranium of Dinornis, referable by its size to the D. dromioides, was kindly trans- 

 mitted, with other bones of the same genus, for my examination by Mr. Swainson*. 

 It has suffered nearly the same kind and degree of mutilation as the larger cranium ; 

 the basi-sphenoid, with all the rostral part of the skull, having been broken away ; but 

 the supra-orbital ridges and fore-part of the frontal region of the cranium are more entire 

 (Plate XXXIX. figg. 4 — 6). The breadth of the cranium across the mastoids is two 

 inches, seven lines ; the length to the anterior border of the os frontis (not entire in the 

 larger specimen) is two inches, eight lines ; the breadth across the post-orbital angles is 

 two inches, two lines ; the breadth between the temporal fossje is one inch, nine lines. 



The smaller size of the present cranium, as compared with the preceding specimen, 

 does not depend upon the immaturity of the individual : not only are the sutures almost 

 as completely obliterated (and this takes place much later in Struthious birds than in 

 birds of flight), but the ridges defining tlie attachment of the muscles are as strongly 

 marked, and indicate not only a full-grown but an old bird. 



The large size and vertical plane of the foramen magnum ; the broad, low, supra- 

 occipital region (figg. 4 & 5, a) , sloping from below upwards and forwards ; the almost flat 

 parietal surface {ib. 7), continued directly forwards into the broad, downward sloping 

 frontal region {ib. ii) ; the wide and deep temporal fossae (ib. 6) ; the small orbits [ib. u') 

 and expanded olfactory chamber (fig. 6, is) ;— all repeat the peculiar generic characters 

 of the cranium of Dinornis which are exhibited in the larger specimen. 



The specific distinction of the smaller cranium is shown by the less produced and 

 sessile occipital tubercle (figg. 4 & 5, i) ; by the absence of the two fossce on the back- 

 part of the descending plate of the basi-occipital ; by the wider temporal fossje, divided 

 behind from the occipital surface by a common ridge (fig. 5, r), not by a flattened tract ; 

 — and if the value of this difference should seem to be diminished by the known changes 

 in the development of the temporal muscles in the progress of age, it applies in the 

 present instance in favour of the specific distinction of the smaller cranium ; for the less 



* In the note accompanying the specimens that eminent ornithologist says, " They are from the North 



Island I have no idea that this strange group of Birds is any longer in existence, notwithstanding all 



the stories of the natives and others. If any may be alive they will probably be found in the Middle Island, 

 which may be almost said to be \iniahabited, except on the coast." 



VOL. III. PART IV. 2 U 



