June 1, 1895.] 



KNOWLEDGE. 



127 



the lower Eocene of England and France known as 

 Gastornis. In Brontnrnis this bone measures thirty inches 

 in length, and in Pliororhm-his about fifteen and a half 

 inches. In the latter genus the tarso-metatarsus (Fig. i) 

 has a total length of about twelve inches ; while that of the 

 former (Fig. 5) measures sixteen and a half inches In 

 most cases, as shown in Fig. 4, d, the first toe was present, 



but this is stated to have been 

 wanting in some forms. A 

 further difference between the 

 two genera is to be found in 

 the form of the terminal joint 

 of the toes ; in Brontnmis (Fig. 

 5, b) this bone having a marked 

 lateral expansion at its upper 

 end, whereas in Phororhachis 

 it tapers gradually from one 

 extremity to the other. While 

 the vertebrse exhibit well- 

 developed pneumatic cavities, 

 the leg-bones would appear to 

 have been filled with marrow, 

 like those of the modern 

 Eatitse. 



After a careful description 

 of all the known remains of 

 these gigantic birds, Senor 

 Ameghino comes to the con- 

 clusion that while they cannot 

 be placed among the Ratitae, 

 as now defined, neither can 

 they well be included among 

 the flying birds, or Carinatfe, 

 as they agree with no living 

 members of that group. With 

 this conclusion I agree entirely. 

 In respect to the structure 

 of their quadrate-bone the 

 Stereomithes are clearly more 

 closely allied to the Carinatfe 

 than are any of the modern or 

 later Tertiary Ratita? ; but from 

 the extraordinary structure and 

 great relative size of their skulls, it is practically certain that 

 they cannot be regarded as ancestral types of the latter, in 

 all of which (with the exception of the New Zealand kiwis, 

 where the bill has undergone a special elongation) the 

 skulls are imusually small. 



It is accordingly evident that the Stereomithes and the 

 Ratitfe have originated, quite independently of one another, 

 from flying birds ; and this might lead to the conclusion 

 that the latter have likewise had a multiple origin, and that 

 the diflerent family groups into which they are divided have 

 no real relationship with one another. Without denying 

 that this may be the case, it must be remembered that all 

 the modern Ratitfe, together with the moas, agree with one 

 another in having but a single upper articular head to the 

 quadrate-bone, and likewise in the short and squared 

 coracoid, as well as in certain other features. And as the 

 first of these peculiarities is not an adaptive one, this at 

 least is scarcely likely to have been evolved in all cases if 

 the different families of that group had originated 

 independently of one another. 



The Patagonian beds from which the remains of the 

 Stereomithes are obtained have been generally assigned 

 by the South American palasontologists to the lower Eocene 

 division of the Tertiary era ; but this date is certainly too 

 early, and they are more probably of Miocene or Oligocene 

 age. Admitting this, the question then arises whether 



Pig. 



18 of 



. 4. — Left tai'so-inetatar- 

 Phoi'orachis. a, from 

 in front ; h, upper end ; c, d, 

 back view of upjier and lower 

 <'nds ; e, inferior extremity. 

 About two-fifths natural size. 



there are any older Tertiary birds which can be regarded 

 as related to the Patagonian forms ; and we naturally turn 

 to the Eocene tTcistoniis, already mentioned, allied to which 

 is another bird from the same European strata, known as 

 Jiiisoruis, and a third from the equivalent strata of North 

 America, to which the name Diatrt/iim has been applied. 

 Unfortunately, we know the skulls of these birds only by 

 fragments, but they appear to have been of relatively large 

 size, although such restorations as have been given malie 

 them much more depressed than those of the Stereomithes. 

 This, however, might be a feature of not more than family 

 value. There are, however, other difl'erences of consider- 

 ably more importance, one of these being the circumstance 

 that the component bones of the skull remained separate 

 throughout life, instead of uniting at a very early period 

 as in all existing birds ; while anotlier is to be found m 

 the shortness of the bony union between the two branches 

 of the lower mandible. It has also been considered not 

 improbable that the upper jaw of Gimturnls was furnished 

 with a pair of large teeth ; and if this should prove to be 

 well founded, it will be evident that the group must have 

 branched oft' from flying birds at a time when the latter were 

 still toothed. Apart from this, although thers appears to 

 be no evidence as to the form of the head of the quadrate- 

 bone, the tibia of these Eocene birds agrees with that of 

 the Stereomithes, and the fragments of the coracoid 

 indicate that that 

 bone was of the same 

 elongated type. As 

 the extinct Pata- 

 gonian Ungulates 

 show remote indi- 

 cations of affinity 

 with some of those 

 of the early Tertiaries 

 of Europe, it is 

 accordingly not im- 

 possible that there 

 a somewhat 

 relationship 

 the Stere- 

 on the one 

 hand and Gastornis 

 on the other. What 

 the nature of this 

 relationship (if such 

 there be at all) may 

 be, it is impossible at 

 present to determine ; 

 but it may be con- 

 sidered pretty certain 

 that neither the 

 Stereomithes nor the 

 (iastornithiilcB can be 

 henceforth included 

 in the Ratitie, and 

 hence that that group 

 is of comparatively 

 modern origin. 



In articles which have already appeared in Knowledge, 

 it has been shown how widely different were the ancient 

 Tertiary mammals of South America from those of all 

 other parts of the world, and we have now evidence to 

 show that the same was the case with the flightless birds. 

 Althoiigh now, owing to the land- connection with the 

 northern half of the New World, its fauna is less peculiar 

 than it was in past epochs, yet it is still sufficiently dis- 

 tinguished to allow Tropical and South America to form 

 one of the three primary zoological divisions of the globe. 



may be 

 similar 

 between 

 ornithes 



B A 



Fra. 5. — a, right tarso-metatarsus, and 

 B, toe-bones of Bronlornis. About one- 

 fifth natural size. 



