On Lost Forms betiveen Birds and Reptiles, 359 



always be able to produce his title-deeds, in the way of direct evi- 

 dence, or take the penalty of that peculiar discomfort to which I 

 have referred. 



You will not be surprised, therefore, if I take this opportunity of 

 pointing out that the objection to the doctrine of Evolution, drawn 

 from the supposed absence of intermediate forms in the fossil state, 

 certainly does not hold good in all cases. In short, if I cannot pro- 

 duce the complete title-deeds of the doctrine of animal Evolution, I 

 am able to show a considerable piece of parchment evidently belong- 

 ing to them. 



To superficial observation no two groups of beings can appear to 

 be more entirely dissimilar than Keptiles and Birds. Placed side by 

 side, a Humming-bird and a Tortoise, an Ostrich and a Crocodile, 

 offer the strongest contrast, and a Stork seems to have little but 

 animality in common with the Snake it swallows. 



Careful investigation has shown, indeed, that these obvious differ- 

 ences are of a much more superficial character than might have been 

 suspected, and that Eeptiles and Birds do really agree much more 

 closely than Birds with Mammals, or Keptiles with Amphibians. But 

 still, '' though not as wide as a church-door or as deep as a well," 

 the gap between the two groups, in the present world, is considerable 

 enough. 



Without attempting to plunge you into the depths of anatomy, 

 and confining myself to that osseous system to which those who desire 

 to compare extinct with living animals are almost entirely restricted, 

 I may mention the following as the most important differences between 

 all the Birds and Eeptiles which at present exist. 



1. The pinion of a Bird, which answers to the hand of a man or 

 to the forepaw of a Reptile, contains neither more nor fewer than 

 three fingers. These answer to the thumb and the two succeeding 

 fingers in man, and have their metacarpals connected together by firm 

 bony union, or anchylosed. Claws are developed upon the ends of 

 at most two of the three fingers (that answering to the thumb and the 

 next), and are sometimes entirely absent. 



No Reptile with well-developed forelimbs has so few as three 

 fingers ; nor are the metacarpal bones of these ever united together ; 

 nor do they present fewer than three claws at their terminations. 



2. The breast-bone of a Bird becomes converted into membrane- 

 bone, and ossification commences in it from at least two centres. 



The breast-bone of no Reptile becomes converted into membrane- 

 bone, nor does it ever ossify from several distinct centres. 



3. A considerable number of caudal and lumbar, or dorsal, ver- 

 tebrae unite together with the proper sacral vertebrse of a Bird to 

 form its " sacrum," In Reptiles the same region of the spine is con- 

 stituted by the one or two sacral vertebree. 



4. In Birds the haunch-bone (ilium) extends far in front of, as well 

 as behind, the acetabulum ; the ischia and pubes are directed back- 

 wards, almost parallel with it and with one another ; the ischia do not 

 unite in the ventral middle line of the body. In Reptiles, on the 

 contrary, the haunch-bone is not produced in front of the acetabulum ; 



