472 Notices of Memoirs — C. W. Andrews on Stereornithes. 



Abstkacts of Papers read at the British Association Meeting, 



Ipswich, September 1895. 

 III. — Some remarks on the Stereornithes, a Group op Extinct 

 Birds op Patagonia. By C. W. Andrews, B.A., B.Sc, F.G.S., 

 Assistant in the British Museum. 

 rpHE history of the discovery of the extinct birds of Patagonia 

 _L is briefiy given, and the more important of the opinions that 

 have been expressed as to their affinities are noticed. 



The age of the deposits in which the remains occur is probably 

 much later than the Eocene, to which they are usually referred, and 

 may perhaps be taken as Miocene. 



The structure of the skull and skeleton of Phororhacos, as de- 

 scribed by Ameghino in his recent valuable and interesting paper, 

 is discussed and compared with that of some other birds. In the 

 absence of actual specimens it is impossible to arrive at any very 

 definite results, but it may be suggested that some, at least, of 

 /7 the Stereornithes may be related to the Geniformes, particularly to 



the Dicholophi. Others of the group are imperfectly known, but 

 some of them appear to differ considerably from Phororhacos. It 

 therefore seems probable that the " Stereornithes " may include a 

 somewhat heterogeneous collection of birds which have lost their 

 power of flight in consequence of some local conditions affecting 

 their mode of life, and in correlation with the reduction of their 

 wings attained a greatly increased size. A similar instance is to be 

 found in the extinct birds of New Zealand, where the Dinornithid 

 Jpteryx, Cnemiornis, Aptornis, etc., all flightless, and for the most 

 part of great size, formerly coexisted. In most cases, as soon as 

 the peculiar conditions to which they are adapted pass away, such 

 specialized forms become extinct, and this appears to have happened 

 to the Stereornithes. 



There seems no reason why such groups of flightless birds should 

 not arise at any period and in any region, providing the conditions 

 of life are favourable ; indeed, the Gastornithid^, in the Eocene of 

 Europe, and the Stereornithes, in somewhat later deposits in South 

 America, may be taken as instances of this. 



In the Stereornithes the keel of the sternum was no doubt reduced 

 or absent, so that they were " Eatites " in the narrowest sense of the 

 word ; but on the other hand, they can hardly be referred to the 

 sub-class Eatitge as usually undei'stood, the members of which possess 

 numerous primitive characters which point to the conclusion that 

 they are the survivors of a group, or perhaps several groups, not 

 necessarily contemporaneous, of ancient and generalized bii'ds in 

 which the power of flight had been lost, perhaps even in the 

 Secondary period. Unfortunately, the want of any means of dis- 

 tinguishing truly primitive characters from those which Fiirbringer 

 calls " pseudo-primitive, " which are acquired in the course of 

 retrogression (ruchbildung), makes it impossible to determine the 

 exact relation of the " Katitas " to other flightless birds, and until 

 a long series of remains from different horizons is available, this 

 uncertainty must remain. It seems very doubtful whether Gastornis 

 is at all related to the South American forms. 



