388 On the Skull ^'c. of iEpyornis. 



Humerus, 



In the collection there are several small bones which I 

 believe are rudimentary humeri of jEpyornis, though some 

 o£ the specimens are so different from other avian humeri 

 that it is by no means certain that this interpretation is 

 correct. In the case of the bone shown in fig. B (p. 386), 

 however, there seems to be no doubt that it is a much reduced 

 humerus of a bird, presumably one of the ^pyornithidse ; 

 the length of this specimen is 63 mm. The upper end of 

 the bone is modified in a manner similar to that seen in 

 Aptornis, the head being placed very obliquely, and the inner 

 trochanter {tuberculum mediale, t.m.), which is extremely 

 prominent, rising above it ; the pectoral crest [cr.l.) is reduced 

 to a slightly projecting rugose surface. The lower end is 

 somewhat similar to that of the humerus of Casuarius, but 

 is still further reduced, the radial and ulnar trochlese uniting 

 completely to form a single articular surface. The nature 

 of the specimen shown in fig. C (p. 386) is more doubtful, 

 yet it so closely resembles the last in the form of its lower 

 portion that I am led to believe that it is an avian humerus 

 also ; its upper end is, however, very different and peculiar. 

 The head is large and nearly globular ; it rises above the mas- 

 sive inner trochanter {tuberculum mediale), and is separated 

 from it by a well-marked groove {incisura collaris) . Here, 

 also, the pectoral crest is reduced to a mere rugose prominence. 

 If these two bones are in fact humeri of species of the 

 ^pyornithidse, they probably belong to different genera, a 

 question which it is to be hoped will be settled by the dis- 

 covery of complete skeletons of these interesting birds. 



EXPLANATION OF THE PLATES. 



Plate VIII. 



Skull and Mandible o/-^pyornis. 



Fig. 1 . Cranium from above. 



2. Cranium from behind. 



3. Cranium from side. 



4. Premaxillse. 



5. Imperfect mandible from above. 



