6 BULLETIN 2 08, UNITED STATES NATIONAL MUSEUM 



birds showing a midventral symphysis of the clavicles, as in the wood- 

 peckers, though no hypocleidium is present in any of them. 



In his study of the functional anatomy of birds' feet, Steinbacher 

 (1935, pp. 259-260) finds the honey-guides to be more like the barbets 

 than the woodpeckers. 



Bearing in mind the differences of opinion, and the additional data 

 just outlined, it seems that the barbets have the greatest number of 

 structural characters in common with the honey-guides, and may 

 therefore be looked upon as being, in all probability, their closest 

 living relatives. It appears that both groups may have descended 

 from a common stock, rather than one from the other. The two 

 families agree in the following characters (in addition to those common 

 to all the groups of piciform birds): Transpalatine process absent; 

 sternum with double notch; manubrium pointed, not bifurcate; oil 

 gland tufted; vinculum present between deep flexor tendons of legs; 

 similar, nonpennaceous structure of barbules at the base of the contour 

 feathers; similar insertion of Tensor patagii brevis; thigh muscle 

 formula AXY; Ambiens muscle absent, the Dermotensor patagii 

 joining the Tensor patagii longus, which, in turn, is joined by a strong 

 slip from the Pectoralis propatagialis ; biceps slip absent; Expansor 

 secundariorum absent; only one carotid artery, the left, present; gall 

 bladder long and tubular; the Peroneus brevis with a large tendon of 

 insertion; Peroneus longus absent, cervical haemopophyses single, 

 sharp, channeled; contour feathers with an aftershaft. (List of char- 

 acters largely compiled from the accounts by Lowe, Gadow, and 

 Ridgway). It should be stated that in slightly more than half these 

 characters the honey-guides, and the barbets, also agree with the wood- 

 peckers. From the barbets the honey-guides differ in the form of the 

 nostrils, which are set in the center of large nasal fossae and smTounded 

 by a broad membrane in the Indicaioridae, while in the Capitonidae 

 they are bored directly into the horny rhino theca; the honey-guides are 

 antiopelmous (like the wiynecks and piculets), i. e., the first, second, 

 and fourth toes are connected with the flexor hallucis longus tendon, 

 and the third toe with the flexor digitorum longus; the honey-guides 

 are 9-primaried while the barbets are lO-primaried. In fact, except 

 for the oscine Passeres the family Indicatoridae forms the only 9- 

 primaried group, and, as Miller (1924, p. 315) pointed out, some mem- 

 bers of the family are 9-primaried in the strictest sense, as in Pro(/ofisciis 

 the tenth (outermost) primary is entirely lacking. In many other 

 honey-guides the tenth small quill is still present, but even smaller 

 than in any of the Oscines. The barbets have 10 rectrices, while the 

 honey-guides (except for the genus Prodoiiscus which has 10) have 12. 



Some of the characters tabulated by Ridgway (1914, p. 310) to 

 differentiate the Indicatoridae and the Capitonidae do not hold to 



