126 



KNOWLEDGE. 



[June 1, 1895. 



specimen, for the purpose of having a plaster-cast made at 

 the Natural History- iluseum, and I had the greatest difficulty 

 iu making some of the authorities there believe that the 

 specimen belonged to a bird at all — indeed, I am not sure 

 but that I was considered to have made a hopeless blunder, 

 and to have mistaken the claw of a grouud-sloth for the 

 beak of a bird. Be this as it may, the specimens which 



Fig. 2.— Side view of Skull of Phororhachis inflata. About tn-o-fifths natural size. 



Seiior Ameghino has now figured show the entire skull, so 

 that whatever scepticism there may have been on the 

 matter must now disappear. 



Considering first the skull of the Stereornithes, as these 

 birds have been called, this is remarkable not only for its 

 excessively large size and massiveness, but likewise for its 

 peculiar conformation, which is quite unlike that of any 

 other group, either living or extinct. As shown in Fig. 2, 

 the upper mandible of the beak is of great vertical depth, 

 and very much compressed from side to side ( Fig. 3) , with 

 its extremity forming a sharp hook. In common with 

 many existing birds, the cavities for the eyes (Fig. 2, a) 

 are iu free communication, owing to the absence of a ' 

 partition of bone between them ; and these cavities likewise 

 are completely continuous with the preorbital vacuity {c'\, 

 a feature which Senor Ameghino states is unparalleled 

 among existing birds. The nostrils («), which likewise 

 have no dividing septum, are situated high up in the 

 compressed beak, only slightly below the level of the i 

 upper surface of the hinder part of the skull. A featm-e in 

 which the Stereornithes differ from all living Katitfe, and 

 hereby resemble the flying birds, is to be found in the 

 presence of two distinct condyles or heads, by which the 

 quadrate bone f./y articulates to the skull proper. The 

 lower jaw which is abruptly truncated at its hinder 

 extremity, has a large lateral vacuity, and its pointed tip 

 curves slightly upwaids; the symphysis, or union between 

 its two branches, being long and trough-like. Apparently 

 the only living birds in which the extremity of the lower 

 mandible is curved upwards are the South American 

 trumpeters, Psojihiii. \ 



Comparing this extraordinary skull with thos5 of recent 

 birds, one cannot help being struck with a superficial 

 resemblance between the deep and compressed upper 

 mandible with that of the puffins ; but in those birds the 

 conformation of the hinder extremity of the skull is totally 

 different, while the large nostrils are pierced low down in 

 the sides of the beak. In the hooked extremity of the 

 upper mandible, and also in the narrowness of the whole 

 of this region, there is a decided resemblance to the 

 cormorant and the albatross, although in both those 

 birds the beak is of no great depth, while the preorbital 



vacuity is sharply separated from the cavity of the eye. 

 All three agi-ee, however, in the truncation of the hinder 

 end of the lower mandible, while the albatross has a 

 vacuity in the side of the latter, and also no septum 

 between the nostrils. On the other hand, while the upper 

 surface of the skull of the albatross is quite unlike that 

 of the fossil, there is a decided resemblance in this 

 respect in the case of the cormorant, 

 this being especially shown in the 

 projecting processes at the postero- 

 lateral angles. Whether this re- 

 semblance indicates any real affinity, 

 I am quite unprepared to say, 

 but it may be mentioned that both 

 in the albatross and the cormorant 

 the extremity of the lower mandible 

 slopes downwards instead of upwards, 

 while in the latter the symphysis 

 is very short. The American 

 ATiltures also resemble the fossils 

 in their hooked upper mandible and 

 absence of a nasal septum, but 

 differ markedly as regards the rest 

 of the skull. Unfortunately, we have 

 no knowledge of the structure of the 

 palate of the Stereornithes. 



We have likewise no information 

 as to the breast-bone or sternum of the latter, and we 

 cannot, therefore, say whether it resembled the Eatite 

 type in being smooth and 

 flat, or whether it carried the 

 prominent keel of ordinary 

 flyingbirds. Wedo, however, 

 know that the coracoid bones 

 were of the narrow elongated 

 type characteristic of the 

 latter; while we have like- 

 wise information to the effect 

 that the wings were com- 

 paratively well-developed, 

 although incapable of sup- 

 porting these enormous birds 

 in flight. Perhaps they were 

 used to aid in running, as are 

 those of the modern ostrich. 

 As regards the leg-bones, 

 these indicate two very dis- 

 tinct generic types, the more 

 slender of which (Fig. -1) 

 accords in relative size with 

 the relatively slender lower 

 mandible of the typical Pho- 

 rorhdchis : while a larger, 

 stouter, and relatively shorter 

 type (Fig. 5) agrees with a 

 larger, shorter, more up- 

 turned and massive kind of 

 mandible. To this second 

 genus the name lironlornis 

 has been assigned. 



In the tibia of both genera, 

 of neither of which we have 

 figured an example, the lower 

 end has a bridge over its 

 front surface to hold down 

 the extensor tendons; such a 

 bridge being absent in aU 

 the existing Eatite birds, 

 moas of New Zealand, as well as in a gigantic bird from 



Fio. 3.— Upper view of the Skull 

 represented in Fig. 2. 



but present in the extinct 



