PHYLOGENY OF THE PALZOGNATHA AND NEOGNATHA. 261 
In Rhea the ischiadic fissure is closed; the ischia, furthermore, meet one another 
below the vertebral column, and the pubes fuse with them posteriorly. Thus Séruthio 
and Rhea are each unique in the form of the pelvic arch. 
Struthio seems to be a stumbling-block. Thus Prof. Newton writes [65]: “Some 
systematists think there can be little question of the Struthiones being the most 
specialized and therefore probably the highest type of these Orders” (‘“ Ratite”). 
Others, in spite of the great amount of specialization which Struthio has undoubtedly 
undergone, would regard this form as the most primitive, not only of living birds, but 
of the Palwognathe living and extinct. 
According to Fiirbringer, on account of the great number of its primaries, its 
coracoid, and many of its shoulder- and arm-muscles, the form of its pelvis, two-toed 
foot, “‘gewisse Kingeweide, etc., entfernen sie weiter von allen anderen lebenden 
Vogeln, als diese in der Regel unter einander divergiren. Zugleich bietet Struthio 
neben verschiedenen mehr vorgeschritten Specialisirungen progressiver und retrograder 
Natur eine Anzahl héchst primitiver Charaktere dar, die ihre tiefer als die anderen 
Ratiten stellen und durch welche diese sehr alte Form Blicke bis in die friihesten 
Vorzeiten des Vogelstammes thun lasst.” 
Beddard considers ‘“‘that Struthio is removed far from the Dinornithide, as well as 
from other Ratites, by the structure of its palate, which diverges much.” He does not, 
however, go as far as Fiirbringer, for he continues further on: “There are really, 
however, not a large series of characters in which they may be fairly said to be more 
primitive than some other groups. .... ” This last statement is evoked in answer to 
Fiirbringer’s contention that Struthio is really very primitive. 
I find myself in agreement with Beddard: more than this, I believe that we have to 
look to Dromeus and Nor to Struthio for the most primitive of living birds. 
This opinion is based mainly upon a study of the bones of the palate in this and the 
allied forms. These in Dromeus seem to represent the ground type from which, or 
from some closely allied form, the palates of Struthio, Rhea, and Dinornis may be 
derived. The palate of Apteryx must be considered by itself. 
The palate of Struthio compared with that of Dromeus will be found by no means 
so fundamentally different as seems to have been supposed. On the contrary, it is 
contended that the palate of Struthio is a specialized and, in some respects, retrograde 
form of that of Dromeus. 
The palato-pterygoid connection is similar in both. 
The palatine and the forward extension of the maxillo-palatine processes are both 
considerably longer, both actually and relatively, in Struthio than in Dromeus. 
Struthio lacks palatine processes to the premaxilla, and has a degenerate, one might 
almost say vestigial, vomer. Like all degenerate structures, however, it gives some 
certain signs of a former perfection. ‘Thus, in a skull which in this paper is attributed 
to Struthio meridionalis the vomerine limbs extend backwards to within a very short 
VOL. XV.—PaRT v. No. 20.—December, 1900. 20 
