INTEODUCTION. 



I. General BemarJcs on tlie Jacamars and Puff-hirds. 



AccoEDiNG to the scheme proposed in my recent article " On the present State of the Systema 

 Avium " * the Jacamars and Puff-birds form two closely allied families of the Zygodactylous 

 Picariae, which, although quite well distinguished from one another, have no intermediate 

 forms, and must consequently be placed next together in the series. The remaining three 

 families which together with the Galbulidse and Bucconidse constitute the group of Zygodac- 

 tylous Picarise are the Rhamphastidse, Capitonidse, and Indicatoridse. But the three last- 

 mentioned groups are at once distinguishable from the Jacamars and Puff-birds by the tufted 

 oil-gland, the absence of cseca, the imperfect clavicles and other characters, and constitute quite 

 a separate section. 



At the same time it must be allowed that this position of the two families now treated of 

 is not likely to be a permanent one ; and Mr. Forbes has favoured me with the following 

 remarks upon what he believes to be their more rational position in the system : — 



"^As regards the affinities of the Jacamars^ the absence of the ambiens and accessory femoro-caudal 

 muscles, the nude oil-gland and large cseca, and the pterylosis show that it is only amongst the Passeriformesf 

 of Garrod that they can be placed. Of these the Passeres proper and the Caprimulgidse and their allies 

 (including the Owls if they are really related) can be at once excluded from further consideration, their 

 differential characters being too well marked to need notice here. The Trogonidse, Meropidse, Coraciidte and 

 Leptosomatidse remain ; and it is amongst these that the nearest living allies of the Jacamars and consequently 

 Puff-birds must be found. The Trogonidse differ mai'kedly in their peculiar feet (the second instead of the 

 fourth digit being reversed), in the non-desmognatlious skull, in the very passerine pterylosis, in having only 

 one carotid artery J, and in lacking the expansor secundariorum muscle. 



" From the three remaining groups (Meropidge, Coi'aciidse, and Leptosomatidse) the Jacamars and Puff- 

 birds are clearly separable by the structure of the feet and by the distribution of the plantar tendons. 

 Nevertheless it is with these three groups that, in most respects, the Jacamars and Puff-birds have close 

 affinities. Neglecting the feet, the pterylographic differences are perhaps the most evident, the Leptosomatidae 

 having in common with the Coraciidse a well-marked interscapular bifurcation of the dorsal tract not present 

 in any other of these forms. The Meropidae lack the internal ' gular ' branch to the pectoral tract of the 

 Galbulidje, and differ still more markedly in the disposition of their tracts from the BuccouidjE. 



"It may be remarked in conclusion that the Galbulidse and Bucconidse are well differentiated off from 

 the Capitonidse and their allies, which also are anomalogonatous and ' scansorial,^ by the latter having a 

 tufted oil-gland and no cseca, at the same time that the external pectoral branch comes oft" from the main 

 tract near the beginning of the breast. Other important points of difference between the two are tlie 

 imperfect clavicles §, different pterylosis, single carotid, lengthy deltoid, scapula accessoria, and intestiniform 

 gall-bladder of the Piciform birds^ all very different from what occur in the Passeriform Galbulidse." 



* Ibis, 1880, p. 401. t P. Z. S. 1874, p. 119 ; CoU. Tapers, p. 217. 



X Most of the Meropidae likewise have only the left carotid; Nyctiomis, however, has two. 

 § Indicator agreeing in this point with the rest of Garrod's " Capitonidaj." 



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