DISCOVERIES IN AVIAN PALAEONTOLOGY. 403 



the specimens. Several extinct penguins of the genus 

 Palceospheniscus, from so-called Oligocene beds, as well as 

 a number of Pleistocene bird remains, were figured in this 

 work, but by far the most important section is that dealing 

 with the great flightless birds of the Santa Cruz Beds. 

 For the reception of these the authors established a new 

 order, the Stereornithes, which was subdivided into four 

 families, the Brontomithidae (including the genera Bron- 

 tornis and Rostromis), the Stereornithidce (with Phororhacos, 

 Stereornis Mesembryornis and Patagomis), the Dryor- 

 nitkidce (with Dryornis) and the Darwinoriiithidce (with 

 Darwinornis and Oweniornis). Psilopterus (a name which, 

 being preoccupied, was afterwards changed by Ameghino 

 to Pelecyornis), a genus probably related to Phororhacos, 

 was placed in the Cathartidce. 



At the end of the same year Ameghino published a 

 synopsis of the South American fossil birds (9) in which 

 he severely criticised the classification given above. He 

 asserts that nearly all the new genera are merely synonyms 

 of Phororhacos ; the only exceptions being Brontornis 

 which includes Rostromis, and Psilopterus {Pelecyornis) 

 which embraces Patapornis. Examination of the figures 

 given by Moreno and Mercerat shows that in many 

 cases, at least, he is right ; for instance Ste?'eomis is 

 clearly the same as Phororhacos. On the other hand 

 Dryornis, the sole member of the Dry omit hidce, is founded 

 on the distal end of a humerus, which, judging from the 

 figure, is probably that of a large vulture, most likely the 

 Condor ; it may be pointed out that this specimen is not 

 from the Santa Cruz Beds but from a Pleistocene de- 

 posit. 



In this paper Ameghino himself refers all these flightless 

 birds to two families, the Pelecyornithidce (including Pele- 

 cyornis and two new genera, LopJiiornis and Anissolomis) 

 and the Phororhacosidce (with Brontornis, Phororhacos, and 

 a new genus, Opisthodactylus). All these he regards as 

 Ratitce, and in this he was followed by Gadow (10) and 

 Lydekker (11). Subsequently the latter of these writers, 

 relying on the fact that the quadrate in Phororhacos pos- 



