NINTH ANNUAL REPORT. 219 



against the sides of the body. When this area is truncal in ex- 

 tension, or when small apteria are present in adjacent parts of 

 the body, the condition is either wholly vestigial, or dependent 

 on the action of the legs. This remarkable obliteration of apteria 

 (which is paralleled only by the Penguins, and the horned 

 screamer among the Carinatac ) is, without doubt, only a sec- 

 ondary primitive character, although there is not that difference 

 in the pterylosis of the embryo and the adult, which we might 

 expect. The ventral apterium is fairly well developed in the adult 

 Apteryx, which does not rest on its sternum and thus has no 

 sternal callosity. 



As special adaptations of degenerate feathers, are to W noted 

 the well-developed eye-lashes of Ratite birds, especial!}- in the 

 case of the Ostrich. Thev may perhaps be necessary, even in 

 addition to the nictitating membrane, in keeping the eyes clear of 

 dust, which would be abundant in the deserts and plains of Africa. 



The elongate, hair-like, facial feelers and rictal bristles of the 

 Apteryx are. of course, metamorphosed feathers, and subserve 

 the function of touch — most imp(^rtant in this nocturnal, vermiv- 

 orous bird. 



B. Remiges. — The remiges, as we might expect in structures 

 whose sole original function has disappeared, have either dimin- 

 ished in number or run ram]:)ant. In one case only (the Casso- 

 wary) is there a suggestion of change of function, or adaptation 

 to new conditions, although there is just a suspicion that the 

 increase in number of the remiges of Struthio anil Rhea may have 

 some such significance. 



It is evident that the ancestors of the Ostrich and the Rhea 

 used their wings to a much later time than did the forebears of 

 the Emeu, Cassowary and Apteryx. The only data for com- 

 parison which we have at present is the number of remiges in 

 the Archaeopteryx. and the extreme variations which exist among 

 the Carinatac. The following table will i)resent the matter 



clearlv: ^ .^ 



Primaries. biicoxDAUiii.s. Ivkmkiks. 



Ostrich i6 20 36* 



Rhea 12 16 28 



Emeu 7 10 17 



Apertyx 4 9 ' 7 



Cassowary ^ 3 ^ 



Archaeopteryx 6 or 7 10 16 



Humming-bird .... 10 6 16 



Albatross 10 30-40 40-50 



*In one male bird wliicli I i-xamincd tliere were no loss than forty-one. 



