MORPHOLOGY OP THE GALLINACE.E. 241 



It can be seen, even at the beginning of the second week of incubation, that the embryo is 

 that of a bird, for it combines, in one, characters that are diagnostic of three, at least, of 

 the most remarkable types of extinct Reptiles. Thus the upper and lower jaws are 

 growing forwards into a long beak, and the extension of the basi-facial axis is just like 

 what is seen in all rostrate types, e.g., in the Skate, Sturgeon, and Lepidosteus, and the 

 embryonic skull of Ichthyosaurus must have had the same intense " prognathism." But 

 the elongation of the neck and the shortening of the tail remind us of the Plesiosaurus, 

 which type, if it had possessed a long beak, might have done duty, hypothetically, for an 

 early pupal form which was destined to become a bird. But that water-monster never 

 attained to such a dignity. 



The newest evolutional candidates for birdship are the Ornithoscelida — the Iguano- 

 don and his kindred ; I need not say that none of these ever became a bird ; they did 

 grow into something wonderful, and their hind-quarters were modified in the same 

 manner as those of an embryo Humming-bird ; but a creature weighing twenty tons would 

 have required, in the atmosphere of this planet, wings that would have reached " from 

 sea to sea." Was the bird developed from some small kind of Ornithoscelidan ? I think 

 not, nor do I imagine that the fan-tailed normal birds — toothed or with horny jaws — are 

 the proper descendants, slowly or more rapidly modified, of the mysterious Archoeopteryx. 

 That Oolitic form did duty, hypothetically, for a short time as a parental bird ; but Marsh's 

 Toothed Birds of the Cretaceous period suggest that this is a fallacy. The fact that Ses- 

 perornis had cylindroidal vertebrae up to its pelvis, and that it had existed as a type 

 long enough for the abortion of its wings and sternal keel, is proof surely that this short- 

 tailed type had existed for an enormous period of time ; that is, if our evolutional specu- 

 lations have any solid truth in them. 



Anyhow, however long the period has been in which the Bird has arisen from some 

 low form, the time taken, now, in the egg, for the whole of its pre-natal transformation 

 is extremely short — an hour, now, stands for an age, in the past. 



At this stage— my first in this paper (see p. 215)— the hind-quarters are already 

 essentially Ornithoscelidan ; the ilium embraces a long series of sacral vertebrae, and 

 the pubis and ischium have rotated backwards as in those extinct Reptiles. 



The hind limbs correspond very closely at this time with those of the Iguanodon, 

 yet they are very partially ossified, and in some things they are evidently in harmony 

 with what existed in the early young, not the adult, of that large extinct Reptile. 



The wing, at first, has only three digits ; the foot has a proximal rudiment of the 

 fifth, with the first arrested at its upper end. But the ends of the digits are flat aud 

 soft, there is no claw at present ; they are in an amphibian stage at this early date ; 

 all Reptiles pass through that stage, and one Amphibian, namely Dactylethra, does 

 acquire claws. 



The Semipod comes in as a very instructive type, tending to connect the Eowls with 

 the Ostrich tribe ; it is evidently archaic. 



In the present short and very imperfect summary, I, of necessity, refer to the other piece 

 of work on the Fowl and the Hemipod, and also to other papers of mine on the morphology 

 of this bird. 



