THE LIVING WORLD. 
277 
sprang from an ancestral stock with which birds are only remotely connected. 
Their position between reptiles and mammals in our linear system does not indi¬ 
cate any intermediate position in nature, but is simply due to our inability of 
expressing exact relationships. 
“ There are other features which frequently are attributed to the bird class 
as diagnostic, but which really are but of little account; for instance, the modifi¬ 
cation of the jaws into a beak sheathed with horn and destitute of teeth, for not 
only have the turtles and duck-moles similar beaks, but we know now that teeth 
were common in certain groups of extinct birds as they are in reptiles or mam¬ 
mals nowadays. Nor is the laying of eggs and their hatching an exclusive 
characteristic of the feathered tribe, for we have birds which leave the hatching 
to be done by the heat of decaying vegetable matter heaped upon them, while 
the latest indications are that the old report of the monotremes (of the duck-bill 
species) laying eggs, hitherto regarded as a fable, is substantially true. The 
so-called pneumaticity (hollowness) of the bird skeleton, or the peculiarity of the 
bones being hollow and filled with air through the canals, in connection with the 
respiratory organs, has also been regarded as belonging to birds only, but the 
bones of the extinct pterosaurians (winged lizards) and some other forms were 
also filled with air, air canals being present in nearly all the bones of skeletons 
of the larger species, while several recent birds, for instance the kiwis and pen¬ 
guins, are entirely destitute of pneumaticity in any part of the skeleton.” 
THE LINK THAT CONNECTS BIRD WITH REPTILE. 
Other species of extinct reptiles, such as the pterodactyls (wing-fingered, 
or wing-toed), and ramphorynchus (branch-beaked), might also have been 
cited by Mr. Kingsley as combining characteristics common to birds. The 
former, which was about the 
size of a swan, had the pow¬ 
ers of flight highly developed, 
though its structure was very 
similar to that of the bat. 
The latter, while possessing 
membranous wings, was only 
able to use them as a para¬ 
chute, by the extension of 
which it could leap from an 
elevation and sail a consid¬ 
erable distance on a descend¬ 
ing plane. Its size was equal 
to that of a crow, and in . 
many respects its structure was decidedly bird-like. The head and beak were 
those of a bird, except that the bill was long and armed with teeth, a provision 
no longer observable in any of the feathered tribe; but the breast and back 
were those of a bird, save that the extension of the back was vertebrated and 
terminated in a tail of considerable length. The combination of bird and rep¬ 
tile was strikingly illustrated in this curious creature, and well entitles it to 
being considered as the connecting link between the two. 
Though we have the strange anomaly before us of reptiles producing their 
young alive, and of at least two species of quadrupeds that lay and incubate 
THE RAMPHORYNCHUS. 
