PROFESSOR OWEN ON THE GENUS DINORNIS. 17 



Zealand. That sternum may, however, belong to the Palapteryx rohustus : it was ob- 

 tained, it will be remembered, from the same deposit at Waikawaite in the Middle 

 Island, from which the most abundant and instructive evidences of that species have 

 been had. The restoration was unavoidably imperfect, as regards especially the form 

 and extent of the anterior or costal angles (a, pi. 43, vol. iii.), but was sufficiently 

 established to illustrate the nearer resemblance of the sternum in form to that of 

 the Apteryx than to that of any of the larger existing Struthious birds. 



A much more perfect specimen of the sternum (PI. IV. figs. 1-4) of a smaller species 

 of the great wingless birds of New Zealand confirms the general accuracy of the restora- 

 tion attempted in my Memoir of 1846, and affords additional illustration of a near affinity 

 to the Apteryx. For this reason I refer the sternum in question to the genus Palapteryx. 

 Like that of the Apteryx, this sternum is remarkable for its shortness in comparison 

 with its breadth, and for the breadth and depth of the two posterior notches. The chief 

 difference is presented by the anterior border, which extends in almost a straight line 

 from one costal angle to the other. These angles (a, a) are produced into short, broad, 

 subcompressed processes, rounded and thick at their free and expanded ends, and slightly 

 twisted upon their neck, or point of attachment. Only three articular surfaces for ster- 

 nal ribs are indicated (fig. 3), the intervening fossae being very shallow ; and the whole 

 extent of the costal border is shorter than in the Apteryx, and resembles in this respect 

 that in the GalUnae, Pigeons, and Penguins. The coracoid fossae (c, c) are small and 

 unusually shallow ; there is a large depression on each side of the fore part of the con- 

 cave surface of the sternum nearly opposite the coracoid fossae, the bottom of which is 

 cribriform ; numerous small foramina having apparently conducted air from the anterior 

 thoracic cells into the sternum. That bone in the Apteryx shows no trace of such de- 

 pressions. The bone, which is cellular at the thicker parts of the periphery, is very thin 

 and compact at the middle of the body of the sternum. 



The posterior border is marked by two deep and wide angular emarginations leaving 

 a broad middle process with two very long and narrow diverging lateral ones ; but the 

 extremities of all these processes have been broken away. The chief specific distinction 

 of the sternum in question, which is that of a mature bird, from the sternum figured in 

 vol. iii. pi. 43, is its smaller size, and the angular form of the posterior notch, which was 

 rounded at the bottom in the larger sternum, as in the Apteryx. 



A distinct form of sternum, although evidently appertaining to a bird which was de- 

 prived of the power of flight, is that which is represented in PI. IV. figs. 5-8. The 

 specimen is part of the collection obtained by Mr. W. Mantell at Waingongoro, and 

 which was sold by Dr. Mantell to the British Museum ; where, for the facilities afllbrded 

 for describing and figuring the specimen, I feel indebted to the kindness and urbanity 

 of the learned Keeper of the Department, Charles Konig, K.H., and of his able Assistant 

 Mr. Waterhouse. 



Its proportions would justify its reference to a bird of the size of that to which the 



VOL. IV. PART I. D 



