2 Mr. C. W. Andrews on a Group of 



presence of teeth and of a helmet-like crest on the skull, 

 were incorrect, as he himself has since stated. 



In 189], also, MM. Moreno and Mercerat published a 

 catalogue of the bird remains in the Museum of La Plata, 

 giving a number of photographic plates, but, unfortu- 

 nately, no descriptions. In this paper many generic 

 names seem to have been employed on quite insufficient 

 grounds. For the reception of the larger, presumably flight- 

 less forms, the authors established a separate order, the 

 " Stereornithes," which, again, they divided into four families, 

 Brontoruithidse, Stereornithidse, Dryornithidse, and Darwin- 

 ornithidse. Probably, also, some of the genera placed by 

 them under the Accipitres belong to this order. The name 

 " Stereornithes " is now generally adopted, and some authors 

 have included under it the Gastornithidse. 



Dr. Gadow considers that the Stereornithes are ancestral 

 forms of the Ratitse, and further that Mesembriornis is the 

 direct forerunner of Rhea. Ameghino and Lydekker have 

 also regarded them as Ratites, but the latter, having had an 

 opportunity of examining an incomplete skull, and finding 

 that the quadrate has a double head for articulation with the 

 ekuU, has changed his opinion and now considers them as 

 modified Carinates. Probably, in the strict sense of the 

 word, many of these birds are *' ratite,^^ but the gradual loss 

 of the power of flight and the consequent reduction of the 

 pectoral muscles might lead to the loss of the keel of the 

 sternum in any " carinate " bird. 



Up to the present year all these various conjectures as to 

 the nature of these birds were founded on some limb-bones 

 and some very small portions of the skull, but lately 

 Ameghino has published a very valuable paper descriptive of 

 a large series of remains, including the greater part of the 

 skeleton (except, unfortunately, the sternum), of some of these 

 giant birds *. The genus most completely known is Phoro- 

 rhacos, and it is to this that the following remarks chiefly 

 refer. 



* " Sur les Oiseaux fossiles de Patagonie." Bol. Inst. Geogr. Argent. 

 xv.,caliiers 11 et 12. Buenos Ayres, 1895. 



