AVBS. 



93 



A. maximus, but it is worthy of note that in the New Zealand "Wall-case 

 Apteryx the egg is enormous compared with the size of the 25 'tt 

 bird which lays it (see Case GG). 



The living rheas of South America were preceded in the 

 Tertiary period by large birds like Brontomis, of which 

 plaster casts of limb bones are exhibited in Wall-case 25. 

 The two-toed ostriches, which are now confined to Africa 

 and Arabia, ranged into the Indian and south-eastern 

 European regions in Pliocene times. Eemains of Strut hio 

 asiaticus from the Siwalik Formation of India are placed 

 with the skeleton of a modern ostrich in Case JJ. A 

 small piece of limb bone from the Eocene of the Fayum, 

 Egypt, exhibited in Table-case 12, probably represents an 

 ancestor of the ostriches, which has been named Eremopezus 

 eocaenus. 



Wall-case 

 25. 



Case JJ. 



Okder III.— SAURURffi!. 



Birds are proved by their structure to be closely related Table-case 

 to reptiles ; and many of the extinct reptiles exhibit pecu- 13 - 

 liarities which are now exclusively confined to birds. It is 

 therefore interesting to observe that the oldest known birds, 

 which date back to the latter part of the Jurassic period, 

 approach the reptiles more nearly than any existing birds in 

 at least four respects. They are peculiar in (1) the possession 

 of true teeth, (2) the biconcave or flat-ended shape of their 

 vertebrae, (3) the completeness of three clawed fingers in the 

 wing, and (4) the elongated, not tufted, shape of the tail. 

 In allusion to the last-mentioned feature they are named 

 Saururse (" lizard- tails "). 



Of these primitive birds only two satisfactory specimens 

 have hitherto been discovered, both in the Lithographic 

 Stone of Bavaria, which is of the same geological age as the 

 Kimmeridge Clay of England. They seem to belong to two 

 species of one genus, and the first specimen, representing 

 Archmopteryx macrura of Owen, is shown in Table-case 13. 

 The piece of limestone in which the skeleton is preserved has 

 split along the plane of weakness caused by the presence of 

 the fossil itself, so that some of the bones adhere to one face 

 while other portions are retained by the counterpart slab. It 

 is thus necessary to exhibit the two slabs side by side, the 

 one supplementing the other. As shown by the accompany- 

 ing photograph (Plate VI) and the explanatory diagram 

 (Fig. 87), there is a typical bird's " merrythought " (furcula) 



