240 PROF. W. K. PARKER ON THE 



of its members merely by the recovery of a few fossil forms, the value and importance of 

 such relics would be accounted exceedingly great. 



Now I contend that the interest attached to this group is not in the least lessened by 

 the numbers it contains, and the fact that they are still living, are present everywhere, 

 and can be obtained for morphological purposes at every stage of their growth. The 

 acknowledged fact that these warm-blooded types are, in a sense, merely Reptiles 

 in a high degree of modification, greatly increases the interest in their structure, and 

 especially as the linking on of the Class is not to the existing Reptilian forms, but 

 to various groups that once held sway, but that are only known to us now by their bony 

 remains. 



Thus in themselves, as a Class, when we study them from an ornithological standpoint 

 and for ornithological purposes, they are a group rich in interest, but their ontology 

 takes them far outside the ornithological territory. 



A bird is not merely a modified Reptile ; and no true abranchiate amniotic Reptile 

 ever gave birth to, or was metamorphosed into, a bird, either slowly or by an evolutional 

 " leap." 



Those branchiate, non-amniotic forms, the Amphibia and Dipnoi, have a prior quasi- 

 parental claim on the bird ; its development clearly suggests this, and it seems to me 

 that we must seek for the origin of both Reptiles and Birds amongst imagined forms of 

 those half-fishy sort of creatures. 



The resemblance in its structure and development of a Bird to a Reptile is not at first 

 to be understood off-hand easily, it is a very complex matter ; for a bird is like one kind 

 of Reptile in one thing, and resembles others in other things. Note one thing, namely, 

 that a bird is extremely unlike a flying Reptile (Pterosaur), and that the types that help 

 most in this comparison are the Ichthyosaur, the Plesiosaur, and the Dinosaur. 



If anatomists had gone on in the old way, simply comparing the adult of one type of 

 Vertebrates with the adult of another, the whole subject must have still slept in dark- 

 ness ; the study of the development forces the mind into evolutional speculation. 



Nearly half a century has elapsed since my own attention was arrested by this subject, 

 and to-day, instead of finding any place of rest, the necessity for renewed labour is felt 

 by me more strongly than ever. 



In the beginning of this part of my morphological work, which has been taken up 

 again and again, the labourers were few indeed ; now one is almost lost amongst a host 

 of esteemed fellow-workers, whose researches are ever shedding new light upon this 

 difficult but delightful subject. 



In the present paper I have only lightly touched those regions of the skeleton of the 

 Fowl which have already been figured and described. Nevertheless, the whole skeleton 

 of the Chick is shown, just at the end of the first or beginning of the second week of 

 incubation. The Fowl is but a halfway kind of bird, between an Ostrich and one of 

 the highest types of a songster ; and yet the rate of development in it is marvellously 

 rapid, for even this medium kind of bird ripens its young in the egg at four times the 

 rate of that of an embryo Crocodile ; three weeks serves for the Chick, three months are 

 required for that Reptile, and six months for a Skate. 



