THE HONEY-GUIDES 7 



the extent that he thought. The two groups are essentially similar in 

 their pterylosis, the chief difference being that in the barbets (it is 

 not known if this is true of all the genera) there is a noticeable, some- 

 what diagonal apterium on either side of the chin and throat, whereas 

 the entire chin and throat are feathered in the honey-guides; also, 

 the spinal tract is interrupted posterior to its bufurcation on the back 

 in the barbets while in the honey-guides the two branches come 

 together posteriorly (and these two branches are larger as well). 

 The posterior portion of the spinal tract is narrow and mediodorsal in 

 Indicator and there is a short, disconnected supracaudal tract on 

 either side extending anteriorly to about the level of the posterior 

 union of the bifurcations, while in the barbets the posterior end of the 

 spinal tract itself divides to form a circle around the uropygium, 

 leaving the mediodorsal area unfeathered and encompassing the two 

 supracaudal tracts in its course. The apteria generally are somewhat 

 more extensive in the barbets than in the honey-guides. The dif- 

 ferences mentioned by Ridgway in the size and shape of the bill and 

 in the relative length of the outer primaries are scarcely characters 

 of familial significance. There is, however, a notable difference in 

 the syrinx, but it must be remembered that our comparison is based on 

 three species of honey-guides {Indicator indicator, I. maculatus, and /. 

 exilis) and a single kind of barbet (Megalaema asiatica). In the 

 honey-guides the lower end of the trachea is formed into a solid, 

 osseous box by the fusion of several of the lowermost rings; the first 

 bronchial semiring, to which is attached the single pan* of intrinsic 

 muscles, is considerably swollen and much larger than the subsequent 

 ones. In the one barbet examined the syrinx is of a simple tracheo- 

 bronchial form, the last rings are not fused at all, but are distinct, 

 and there are no intrinsic muscles. 



An important character in which the honey-guides agree with the 

 barbets and differ from the woodpeckers is the form of the tongue, 

 which is short and not extensible or protrusible. 



The phylogeny of the species of honey-guides within the family now 

 seems fairly clear, although in the past literature it seemed otherwise, 

 as may be sensed from the disparity in the treatment presented 

 between even two linear lists such as those of Sharpe's hand-list of 

 1900 and Peters' of 1948. Sharpe lists the genera in the following 

 order: Indicator, Prodotiscus, Melignomon, while Peters gives Prodo- 

 tiscus, Melignomon, Indicator, Melichneutes. For such a small avian 

 family, containing only 11 species, the Indicatoridae has numerous 

 and divergent subdivisions — 4 genera, of which 2 {Melichneutes and 

 Melignomon) are monotypic and 1 {Prodotiscus) has only 2 species, 

 while the only genus with several members {Indicator, with 7 species) 

 is readily divisible into 3 subgenera (4 species in subgenus Indicator, 



