14 BULLETIN 208, UNITED STATES NATIONAL MUSEUM 



variegatus; the interpalatine spurs are relatively longer than in /. 

 variegatus, agreeing in this respect with /. indicator; the pterygoids 

 are slightly more slender, less widened anteriorly than in /. variegatus. 

 The skull of I. maculatus agrees in all respects with that of /. variegatus. 



The gizzard is thin-walled, quite remarkably so in 7. minor, I. 

 indicator, I. xanthonotus, I. variegatus, I. maculatus and I. exilis; 

 in Melichneutes robustus it is slightly more muscular, i. e., thicker, 

 and in Prodotiscus regulus it is thicker than either. My observa- 

 tions are anticipated by similar findings on /. minor by Sclater (1870, 

 p. 178) and Blanford (1870, p. 308). 



Tongues of Melichneutes robustus. Indicator maculatus, I. minor, I. 

 variegatus, and I. exilis were examined. They are all similar to the 

 tongues of several barbet genera with which they were compared, and 

 show no special adaptation towards cerophagy. The tongue of 

 Melichneutes is slightly narrower and longer than that of Indicator 

 maculatus and has a slight basal restriction not noticeable in the latter. 



After studying the various families of piciform birds Beecher 

 (1953, p. 298) concludes that the "jaw muscle pattern shows a strong 

 facies resemblance in all . . . . The honey-guides have the least 

 specialized pattern and may represent the ground plan from which 

 the other families have been derived, though other indications are 

 that the barbets are nearer the ancestral stock .... Bills and 

 feeding habits suggest close but disjunct relationships in a single 

 series and plumage suggests origin of piciform families from the 

 barbets or an ancestral group with a somewhat less pronounced bUl." 



Phylogeny of brood parasitism 



The parasitic mode of reproduction is known definitely in Indicator 

 indicator, I. minor, I. variegatus, I. exilis, and Prodotiscus insignis. 

 There is suggestive evidence for it in Melichneutes robustus and 

 Prodotiscus regulus. Nothing is known of the breeding of Melignomon 

 zenkeri, the two Asiatic species of Indicator, or I. maculatus of West 

 Africa. The last named is very closely related to 7. variegatus, 

 almost closely enough to be considered conspecific, and it would be 

 siu"prising if it were other than similarly parasitic. Also, Melignomon 

 forms a link between Indicator and Prodotiscus, having the 12 rectrices 

 of the former and the thin bill of the latter; in other words, it is a genus 

 intermediate between two parasitic genera, and is therefore probably 

 not different in its breeding habits. It seems safe to say that the 

 parasitic habit is older in the family Indicatoridae than is the evolution 

 of the group into its present generic sections, the two most divergent 

 portions of the family, Indicator and Prodotiscus, being parasitic. 

 Indeed, it appears that the parasitic habit is probably older in the 



