660 REPORT OF NATIONAL MUSEUM, 1893. 



Till' Jacuiiii, like the Iloactziu and Mouud Builder, acquires its full 

 activities at an early date, and Hudson says : 



While I was looking- rlosely at one of the eggs lying in the iialni of my hand, all 

 at once the cracked shell parted, and at the same moment the yonng bird leaped 

 from my hand and fell into the water wliere it swam rapidlj' to a small mound and 

 escaping from the water, concealed itself in the grass, lying close and perfectly 

 motionless like a yonug jilover. 



lam quite sure that the young bird's sudden escape from the shell was the result 

 of a A'iolent effort to free itself, inspired by the loud persistent screaming of the 

 parent birds Avhich it heard while in the shell. 



In the jacanas belonging to the genus Metopidius the spur is much 

 reduced in size, but the bone of the wing itself is so modified as to 



become available as a weapon, 

 being flattened and widened so 

 as to be a scimeter on a small 

 scale (fig. 6). The apparent draw- 

 back to this weapon lies in the 

 fact that, like a two-edged sword, 

 it must cut both ways, and unless 

 the skin immediately over it is 

 particularly dull and insensible 

 rig*5- Metopidius can not strike an 



FOREARM OF AFRICAN TACANA, METOpmius jidvcrsary Avithout feeling the 



Ah RIC ANUS. *' C3 



Katinalsize. ctiectS Of the blOW hiuiSClf. 



CM. N„. 18785, 1, s. N. M. Whether or not this tends to pro- 



mote peacefulness we do not 

 know, but from what we know of bipeds, who claim to be higher in 

 the scale of life, it may be presumed that Metopidius does not mind 

 being hurt himself provided the "other fellow" is hurt still more. 



Largest and most formidable of all spur- winged birds are the Screamers 

 {Anhimida;), three species of birds related to the ducks, although they 

 do not look it, and restricted to South America.* 



These birds have two si)urs, instead of one, upon the outer part of the 

 wnig (fig. 7), the outermost a short affair, the inner an ugly three-sided, 

 stiletto-like blade, about an inch and a quarter long and almost as sharp 

 as a needle. In fact, it is not unlike part of one of those large needles 

 used by sail-makers known as roping needles, and it would seem quite 

 capable of being driven completely through a man's hand by a stroke of 

 the screamer's i)owerful wing. And yet we are told that the screamers 

 are peaceable birds, associating amicably in large flocks, so that this 

 array of spurs, like our modern ironclads, is strictly in the interest of 

 peace. 



* South America is particularly rich in anomalous birds, remnants or relics, one 

 luiglit say, of a bygone avifauna. The Hoactzin, Opisthocomiis cristatus, forms au 

 order by itself, and the three species uf screamers, Anhbna anhima, Chaiina chaiuuia 

 and C. derbhia form another. So do the Tinamous (Crypfuri), while the Trumpeter 

 (Psophia crepitans), Cariama (Cariama cristata). and Guacharo Bird {Stcatontis cari- 

 pensis) each and all are isolated forms. 



