PHTLOGENY OF THE PALiEOGNATILE AND NEOGNATHCE. 239 



In the Crypturi we have a second modification (fig. 5 b, p. 240). The post-axial fleshy 

 moiety has here apparently degenerated so as to be represented only by the vestigial 

 muscular slips from the body of the pre-axial portion, which is thick and fleshy. The 

 vinculum elasticum represented in Rhea by a rudiment only — by rudimentary I mean 

 nascent, not vestigial— is here increased to form a great tendinous sheet. We may 

 suppose that this is an improvement on the proto-carinate form seen in Rhea. 



In Opisthocomus (fig. 5c, p. 241) both pre- and post-axial moieties are fleshy. The post- 

 axial shows the first indication of the complex vinculum elasticum of the Neognathce. 



In Leptoptilus the pre-axial portion is almost entirely tendinous. Proximally, the 

 tendon divides, one branch running directly to the ulnare, and one fusing with the 

 anterior border of a muscular post-axial portion throughout the greater part of its 

 length, finally trending upwards to join the main pre-axial tendon on the ulnare. 

 This last, muscular, post-axial portion apparently represents the broad strap-shaped 

 portion of Rhea ; it differs therefrom only in that it is inserted into the first cubital 

 instead of the first metacarpal remex. 



There are numerous other modifications, varying in complexity, to be found amongst 

 the Neognathce, a study of which would probably yield important results. 



The wing of Rhea represents, probably, as Dr. Gadow — to whom I showed these 

 facts — remarks, a proto-carinate form. 



In the manus of Rhea, Mr. Beddard writes, " we have more evidence of defeneration 

 than in Struthio. There are, in the first place, only twenty-one muscles at most, and 

 some of these are much simplified. 



"The muscles that appear to be totally wanting are (1) the extensor digitorum 

 communis, (2) the pronator profundus. 



" The extensor indicis is only represented by the belly arising from the wrist. The 

 flexor sublimis may possibly be represented by a slip of muscle arising from the 

 tendinous edge of the flexor metacarpi uluaris .... 



"The origin of the biceps is peculiar; it arises not only from the coracoid spine by 

 a rounded tendon, but also by a sheet of tendon edged with muscle from the whole of 

 the coracoid and from just an adjacent bit of the sternum. It is inserted on to both 

 radius and ulna. 



" As in the Ostrich, the radio-metacarpalis centralis arises from the ulna. In Rhea 

 there is a special peculiarity in the presence of a muscular slip running from the 

 tendon of the extensor metacarpi ulnaris near to its insertion to the extensor indicis. 

 Finally the ectepicondylo-ulnaris is distinct." 



Of Struthio, Mr. Beddard writes that, " in spite of the small size of the manus .... 

 relatively to that of flying birds, there is but little, if any, evidence of degeneration in 

 its musculature. On the contrary, indeed, for it might be said that the wing-muscles 

 of Struthio are less degenerate, or at any rate less modified, than those of Carinales, in 

 that amount of muscle compared with tendon is greater. The coin plication of the 



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