Vlll 



INTRODUCTION. 



I. The Bat, in which the humerus is long and slender, with a small 

 pectoral ridge. Ulua rudimentary, attached to the curved radius, 

 which coutititutes the bulk of the forearm ; carpus composed of 

 6 boned ; the metacarpal bones 5 in number, separate and dis- 

 tinct ; the phalanges generally 2 in number ; thumb, and iu some 

 the index finger surmounted by a claw. 



II. The Ptekodactyle, in which the humerus is short and straight, 

 very broad at head, with angular and prominent pectoral ridge ; 

 ulna and radius distinct, of nearly equal size ; carpus composed 

 of 5 bones ; metacarpus of 4 tones, separate and distinct ; 1st 

 finger with 3 joints, 2d with 4, 3d with 5, 4th with 4 joints, 

 all provided with claws, with the exception of the 4th, which is 

 remarkable for the extraordinary development of its several 

 joints. It is from this last mentioned finger to the base of the 

 foot that the skin was stretched by which the animal was en- 

 abled to fly. 



f III. The Bird, in which the humerus is curved, more or less slender; 

 pectoral ridge prominent, not angular ; ulua large, curved, not 

 united with the slender and more diminutive radius; carpus of 

 2 bones ; metacarpus of 2, sometimes of 3 bones — the first being 

 small and cylindrical, the other two of larger dimensions and 

 united so as to form a bone resembling the bones of the forearm ; 

 ulnar phalanx of 1 joint, united to the radial which is composed 

 of 2. 



The power of sustaining flight not dependent upon the ex- 

 pansion of skin, but upon the excessive development of dermal 

 appendages (feathers). 



IV. The Arch.eoptekyx' agrees with the typical bird in general particu- 

 lars, but differs in the number of the metacarpal bones, which are 

 here 4 in number : the 1st and 2d are slender, free and separate 

 from one another ; the 3d and 4th bear considerable resemblance 

 to those of extant birds, in being large, stout, and closely approxi- 

 mated ; but are not, however, united. 



Flight is supposed to have been maintained in the same man- 

 [^ ner as in living birds. 



' ArchoEopteryx Htho(/raphica, H. von Meyer, a fossil of the Lower Jurassic 

 formation of Germany, obtained from the lithographic stone at Solenhofen. 

 It was first made known to science by Prof. Wagner, at a meeting of the 

 Mathematico-Phyjiical Class of the Royal Academy of Sciences of Munich, 

 in 1S>()1, and was more minutely described, by H. Hermann von Meyer, in 

 .Tahrbuch t'lr Mineralogie, 1861, 5')1. 



This remarkable fossil, which is at present exciting such profound 

 attention among anatomists, combines the characters of the bird and the 

 reptile so intimately that it was for a time a matter of doubt to which 



h.i 



