6i6 THE POPULAR SCIENCE MONTHLY. 



ming birds, in spite of their small size, possess a power of rapid flitting 

 and of lightly poising themselves in front of flowers which makes 

 them in some ways the very fullest existing embodiment of the avian 

 ideal. To the same order belong also those most intelligent of all 

 birds, the parrots, whose large heads and crafty eyes mark them at 

 once as the opposite pole from the small-browed, dull-eyed, stupid 

 cassowaries. With them must be ranked the toucans, the barbets, 

 the king-fishers, the trogons, and whole hosts of other beautiful south- 

 ern creatures, among which the feathers have been variously modified 

 into the most exquisite ornamental devices. As for the birds of prey, 

 the eagles, vultures, falcons, hawks, owls, and ospreys must suffice by 

 way of example. 



Even among these central groups of birds, which have varied most 

 and developed farthest from the primitive reptilian character, there 

 are many kinds which retain here and there some small and isolated 

 peculiarities of the ancestral forms. For example, among the duck- 

 like birds, as we have already seen, a single group, that of the mer- 

 gansers, still keeps up some faint memory of the original sharp teeth 

 in the shape of a few horny projections along the edge of the beak. 

 The tooth-billed pigeon of Samoa, a close relation of that early and 

 extinct form the dodo, has also some rudiments of horny teeth ; and 

 the South American leaf-cutters, a primitive set of songless perchers, 

 possess somewhat similar relics of the lost fangs. So, too, our earliest 

 known bird, the archseopteryx, had three free claws on its fore-limb 

 or undeveloped wing ; and traces of such claws turn up in sundry un- 

 connected birds even now, no doubt by reversion to the almost for- 

 gotten ancestral type. In all modern birds, one of the three fingers 

 which make up the pinion still remains free ; and in some species this 

 finger supports an evident claw, sometimes ueed as a spur for the pur- 

 pose of fighting. In many thrushes a rudiment of this claw may be 

 perceived in the shape of a small tubercle or knob at the end of the 

 wing, thus pointing back directly to some remote four-footed and 

 claw-bearing reptilian ancestor. Several plovers have spurs, and so 

 has the spur-winged goose ; while the horned screamer has two on 

 each wing, which he uses with great effect in battling with his rivals. 

 The Australian brush-turkeys have also the rudiment or last relic of a 

 primitive pinion-claw. 



There is another way in which modern birds still partially recall 

 the peculiarities of their reptilian ancestors, and that is in the course 

 of their individual development within the egg. No adult existing 

 bird has all the bones of the tail distinct and separate, like those 

 of the archsDopteryx ; the last joints are all firmly welded together 

 into a solid expanded piece, known from its queer shape as a plow- 

 share-bone, such as the one which I am holding in my hand as the 

 text for this discourse. The use of the plowshare-bone is to sup- 

 port the fan-like quill-feathers of the tail, and also to shelter the oil- 



