1916] Chandler: Structure of Feathers 353 



In the Rallidae the down barbules are short, stout, and deeply 

 pigmented, with short internodes. The pigment is present chiefly 

 in the distal part of the internodes, the minute prongs and the 

 proximal part of the internodes being more or less unpigmented. 

 In Ballus ohsoletus (pi. 36, fig. 107) the internodes reach a length 

 of about 0.035 mm. In GalUnula the nodes are farther apart, 

 while in Cresicus they are nearer together. In Psophia the down 

 is black, as in Ballus, but the nodes are indistinct, and the pig- 

 ment almost uniformly distributed. Eurypya (pi. 36, fig. 106) has 

 barbules which are more elongate and slender, very similar to that 

 of the ardeid forms which have dark down, e. g., Botaurus (pi. 34, 

 fig. 100). Aramus agrees with the cranes in the structure of its 

 down, except that the barbules are not so slender. Cariama has 

 down which is very long and filamentous, with enlarged nodes in 

 all except the more basal barbules. In general the structure seems 

 to be more like that of the Ardeae than like that of any other group. 

 The down of Otis in the general form of the barb and vanules and 

 length of barbules, is of galline type, but the minute structure is 

 very different, the nodes being entirely undeveloped, and the bar- 

 bules being merely long, slender, unmodified threads. 



d) Belationships 



As previously stated, the Gruiformes include a rather heterog- 

 eneous assemblage of bir-ds which show affinities to a number of 

 other groups, but are so generalized in some respects and special- 

 ized in others as to be very difficult to classify. The rails show a 

 striking affinity, as far as their feather structure is concerned, to 

 the Laro-limicolae. The cranes, on the other hand, differ from the 

 Laro-limicolae, but agree with the Ciconiae, in the form of the 

 proximal barbules of the outer vane of the remiges, which have 

 no ventral cilia, while they agree with the Laro-limicolae, but differ 

 from the Ciconiae, in possessing flexules on the breast feathers. 

 Aramus, in the structure of its breast feathers is more or less inter- 

 mediate between the rails and the cranes, while in its back feathers 

 it approaches the peristeropode Galli. Psophia also shows char- 

 acters which are reminiscent of the megapodes and curassows, while 

 Otis comes closer to the alectoropode type in the form of the bar- 

 bules and barbicels. Eurypyga shows so many ardeid characters in 

 the structure of its feathers that it strongly suggests its affiliation 



