1916] Chandler: Structure of Feathers 375 



ing on the distal two-thirds of their length, this portion being fur- 

 nished with a dark pigment (pi. 37, fig. 110), The cells vary from 

 about 20 per millimeter in Coracias affinis to about 28 in Momotus. 



In Halcyon gularis the cells are very short and relatively stout, 

 often over 30 per millimeter, and nearly twice as large in caliber 

 as in Momotus. Only the terminal third of these cells is enlarged 

 and pigmented, thus giving the barbules a very beady appearance. 

 In Ceryle alcyon the cells are longer and more slender, thus being 

 intermediate between Alcyon and the more typical Coraciae. 



In Hydrocorax mindanensis (Bucerotidae), the down barbules 

 have a very peculiar and unusual appearance, the cells being very 

 short and thick, as many as 40 per millimeter, with the nodes not 

 enlarged but marked by two sharp, spiny prongs. The pigment is 

 almost uniformly distributed (pi. 37, fig. 111). In Anthracoceros 

 the cells are longer and the pigment is confined to the middle of 

 the internodes. The nodes are often very indistinct. 



In the Striges the down is very similar to that of the Cuculi- 

 formes. In Buho maximus the barbules have three large nodes on 

 the inner part of the pennulum, shaped more or less like the fruit 

 of a eucalyptus tree. Following these the cells are of the type 

 found in Coracias but very elongate, 9 or 10 per millimeter, with 

 the pigment confined to the distal one-fourth or one-fifth. In Aluco 

 pratincola the structure is similar, but there are usually five instead 

 of three enlarged basal nodes, and sometimes a few globular, droplet- 

 like nodes as in Coccyzus. 



In the Caprimulgi the nodes are usually rather indistinct, espe- 

 cially in the Caprimulgidae, where they are almost imperceptible, 

 although the pigment is restricted to a spot near the distal end 

 of each cell. In Podargus the down is like that of Coracias. 



In Cypseloides and Chaetura, representing the family Cypselidae, 

 the down barbules are similar to those of the Caprimulgidae, the 

 cells having dark pigment in their distal portions and light pigment 

 in their proximal portions, the nodes being indistinct. 



In the Trochilidae the structure of the barbules on the more 

 basal portion of the well-developed downy barb is totally different. 

 The bases of these barbules, unlike those of any other birds except 

 the Passeriformes and Pici, are considerably enlarged and widened 

 on the barbules near the base of the barbs, and have irregular villi 

 on the ventral side, as shown in plate 37, figures 112a and &. The 

 pennula are furnished with large, conspicuous nodes of a peculiar 



