190 STEUCTURE AND CLASSIFICATION OF BIRDS 



undoubtedly nearly related to the Capitonidse, and show 

 slighter but still recognisable points of affinity with the 

 Passeres. The toucans, which are purely tropical American, 

 consist, perhaps, of only one well-marked genus, Bha/mphas- 

 tos, which, however, has been subdivided into Pteroglossus, 

 Aulacorhamphus, Selenidera, and some others. The toucans 

 have a,, tufted oil gland, an after shaft, and ten rectrices. 



The pterylosis (cf . Nitzsch) is characterised by the wide 

 lateral neck spaces. 



The dorsal tract does not divide on the neck, nor is it as 

 a rule ^ continuous throughout. There is a break between the 

 straight anterior portion and the Y-shaped posterior portion. 

 The ventral tract divides in the middle of the neck, and 

 there is a strongly marked outer branch to the pectoral 

 tracts. The femoral tract does not, according to my own 

 experience, arise so early from the spinal tract as Nitzsch 

 figures. 



The intestinal tract of the toucans is short but volumi- " 

 nous, eighteen inches in Bhamphastos dicolorus, nineteen 

 inches in B. carinatus. There are no ccBca. 



The proventriculus is zonary ; the stomach is a weak 

 muscular bag. 



In the liver the right lobe is larger than the left, three 

 times larger in B. carinatus. 



The most characteristic feature in the anatomy of the 

 family concerns the gall bladder ; this has been principally 

 investigated by Forbes.^ It will be seen that the gall bladder 

 is tubular, and of very great length (4-15 inches in a specimen 

 of Bhamphastos dicolorus), as also in the Capitonidae and a 

 fewPicidas (qq.v.) I f ound in itiA. tocard an exceptional state 

 of affairs. As in all (?) toucans, the gall bladder is long, 

 but from the upper extremity two sepa.rate cystic ducts arise, 

 which soon fuse to separate again ; ^ they open, however. In 



' Nitzsch mentions as an exception an unidentified species. And in 

 Selenidera and Aulacorhamphus I could find no break. 



'' ' Npte on the Gall Bladder, &c., of the Toucans and Barbets,' P. Z. S. 

 1882, p. 94. 



' This may perhaps be regarded as a faint indication of the rete found in 

 some reptiles. 



