532 STRUCTURE AND CLASSIFICATION OF BIRDS 



cartilaginous. It is usual to consider that the carpus of 

 Archcsopteryx contained but one carpal ; Hubst, however, 

 asserts that there are two, a radiale and an ulnare. As in 

 modern birds, ArchcBopteryx is generally held to have pos- 

 sessed three fingers, and, again as in modern birds, the second 

 is the longest. HuEST holds that the bird had five, and 

 bases his view upon both fact and theory. As to the former 

 he sees differences in the supposed second and third meta- 

 carpals in the Berlin and London specimens ; it is possible, 

 therefore, that the bones are not the same in the two cases ; 

 hence those of the one may be metacarpals four and five. In 

 the second place he considers that (for reasons which will 

 be referred to more fully immediately) the bird used its 

 fingers for grasping purposes, and that those fingers which 

 were thus used could not have been hampered with feathers 

 of the stiff kind shown in the fossils as apparently attached 

 to them ; hence there were missing digits to which these 

 feathers were attached. In support of this he recalls the 

 young Opisthocomus, which uses the fore limb as a grasping 

 organ before the remiges are developed, and is unable to do 

 so afterwards. 



In any case the metacarpals of the three digits are mov- 

 able, and the number of phalanges progressively increases 

 from two to four. 



The pelvis is ornithic and has a perforated acetabulum ; 

 but the bones, as in no other bird, are not fused but separated 

 by sutures. 



It has been held that the supposed furcula is composed 

 of two ventrally united prepubes, as in dinosaurs (and ptero- 

 dactyles ?) 



The hind limb is avian, with nothing remarkable about 

 it. 



The Arahceopteryx differs from all birds in the following 

 characters ; — 



(1) The tail is as long as the body, with a pair of rectrices 

 fastened to each vertebra. 



(2) The cervical vertebra.' (nine) are fewer than in any 

 other bird. 



