444 The Flying Lizards of the Secondary Eoclcs. 



The reading of Professor Owen's paper before the Royal 

 Society being deferred until the 20th November, Ave were unable 

 to use his valuable anatomical observations and comparisons in 

 our article. It is with pleasure, therefore, that we now record 

 that, in deference to- H. Von Meyer (who had a year before de- 

 scribed and named a single feather from the same quarry which 

 furnished the fossil bird), Professor Owen has withdrawn his 

 MS. name and adopted H. Von Meyer's, Archceopteryx ; giving 

 it, however, the specific name of A. macrurus. The structural 

 peculiarity of the fossil bird, in which it differs essentially from 

 all known examples of the class Aves, is in the apparent pos- 

 session of two unguicular digits, armed with hooked claws, 

 attached to the carpal bones of each fore-arm. These, we 

 suggested, might be analogous to the spurs on the wing of the 

 " Screamer" and " Spur-winged goose ?' but might more 

 probably correspond with the prehensile thumb on the wing of 

 the bat, or the small fingers of the Pterodactyle. 



Professor Owen considers the long tail to indicate a more 

 generalized type than is seen in recent birds, which are special- 

 ized by a form of tail which may be regarded as characteristic 

 of the class. He cited instances of the changes which the 

 vertebras undergo in the embryo of recent birds as illustrative 

 of their affinity with Archceopteryx. Thus, in the embryo of the 

 rook twelve free caudal vertebrae are found ; but before matu- 

 rity five or six of these have coalesced to form the sacrum, and 

 three to make the terminal joint of the tail. In the embryo 

 ostrich eighteen to twenty free vertebras occur, but seven or 

 eight unite in the sacrum, and two or three in the last joint. 

 This arrangement is also found in the embryonal development 

 of the class of Fishes ; for all fishes are Heterocercal (odd or 

 uneven-tailed) in the embryo, although most modern fishes are 

 Homocercal (even-tailed) afterwards. Again, in the Reptilia we 

 have many familiar instances of this general type of structure. 

 In our common fresh-water Tritons, or newts, the full-grown 

 animal retains the long larval tail ; but the long-tailed aquatic 

 tadpole of the frog is gradually transformed into a tailless air- 

 breathing animal, exhibiting probably the highest form of 

 reptilian structure. 



The Solenhofen bird furnishes a fresh exemplification of Von 

 Baer's law of archetypal forms,* and illustrates in a very striking 

 manner that essential similarity of anatomical structure in all 

 animals, which is, perhaps, the most convincing evidence of 

 unity of creative design that can be presented to our minds. 



But we must not dwell upon this inviting subject, having to 

 speak of those singular extinct creatures — reptiles in all their 



* Taylor's Scientific Memoirs, 1853. 



