PHTLOGENT OF THE PALiEOGNATH^ AND NEOGNATHJE. 261 



In Rhea the ischiadic fissure is clossd; the ischia, furthermore, meet one another 

 below the vertebral column, and the pubes fuse with them posteriorly. Thus Struthio 

 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" (" Ratitce"). 

 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 Palasognathce 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 Eingeweide, etc., entfernen sie weiter von alien anderen lebenden 

 Vogeln, als diese in der Kegel unter einander divergiren. Zugleich bietet Struthio 

 neben verschiedenen mehr vorgeschritten Specialisirungen progressiver und retrograder 

 Natur eine Anzahl hochst 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 Dinornithidce, 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 Dromceus and not 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 Dromceus 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 Dromceus 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 Dromceus. 



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 Dromceus. 

 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. 2 



