838 THE AMERICAN NATURALIST. [Vol. XXXVI II. 



well developed, and the posterior margin of the body of the bone 

 presented 710 notches ivhatever, we would be quite at a loss to say 

 what the two species were, but the moment that we added to 

 these osteological characters the fact that it was also known that 

 in the case of one bird it laid its sijigle white egg in a burrow in 

 the ground, while the other laid several w^hite eggs in a little 

 basket-like nest built by itself and found within the cavity of 

 some great hollow tree, we would not hesitate to say but what 

 the skeleton of the first belonged to some one of the smaller 

 petrels, and that of the second to a swift, and very possibly a 

 Chsetura. Your opinion is considerably strengthened when you 

 are told that the bird laying the single white egg had webbed 

 feet, and was strictly a marine species, while the other possessed 

 no such character of the feet, and was a typically insectivorus 

 aerial land bird. When still other characters from other ana- 

 tomical systems and parts are added, the true relations of the 

 two species can be fixed with absolute certainty. In the pres- 

 ent instance they chance to be very remote, although this by 

 no means seemed to be the case when only the few osteological 

 characters were mentioned. Such researches place forms in 

 their proper groups, but to decide upon, or to discover the true 

 relationships of, the families and main groups to each other is an 

 ctuirely different matter and infinitely more difificult. 



It IS very important indeed that we should thoroughly com- 

 I'l-chcnd the origin and evolution of such an assemblage of 

 \crtchratc forms as birds, and it is highly important, too, that 

 chissity existing birds in such a manner that our classification 

 ^ "nvcy> to the mind not only an orderly arrangement of our 

 nowlccl-c upon this subject, but a scheme representing as 

 near as j^ossible the actual and natural relationship of the major 

 and minor groups ot birds as they nowexi.st. To convey such a 

 - ncnie to the mind various plans and methods have been pro- 



- d and adopted by a number of ornithological taxonomers at 



- rent periods of the history of the science. It is not neces- 

 V that all of these be described here,— a few of the more 



T'-'-HMnent examples will answer our purpose. In his memoir 

 '■^>n the Osteology of Gallinaceous Birds and Tinamous," 

 load before the Zoological Society of London on the 25th of 



