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BULLETIN 208, UNITED STATES NATIONAL MUSEUM 



at its anterior end and almost disappears posteriorly. While I have 

 examined only a single example of each of these two, my observations 

 on Indicator xanthonotus bear out exactly what Stoliczka (1873, 

 p. 426) described many years ago for another specimen, writing that 

 the "keel is moderately elevated in front, but after a short distance 

 rapidly diminishes in height, and becomes almost obsolete before 



Prodotiscus regulus 



Prodotiscus insignis 



Prodotiscus 



Melichneutes robusfus 



Indicator indicator 



Indicator exiiis 



Melignomon 



Figure 1. — Phylogenetic tree of the honey-guides. 



it reaches the end of the sternum." Bates (1909b, p. 27) commented 

 on the remarkably depressed body form of Melichneutes, and noted 

 that the sternal keel was shallow; I find it is less weU developed 

 in that species than in any of the other members of the family ex- 

 amined. The aberrant genus Prodotiscus, on the contrary, has a 

 remarkably deep keel. In order to clarify the great differences 



