186- STRUCTURE AND CLASSIFICATION OF BIRDS 



The deep flexor tendons are like those of toucans and 

 barbets (cf. p. 101). 



The tongue ' is elongated, and so are the ceratohyals in 

 relation to it, overlapping and grooving the skull. As a rule 

 among the vs^oodpeckers the right lobe of the liver is larger 

 than the left ; they are equal in Xypoxanthws Bivolii. The 

 gall bladder appears to be absent in Leuconerpes candidus 

 and in Xypoxanthus ; it is long and intestiniform (like that of 

 a toucan) in Gecinus viridis, Dryocopus martins, and Jynx. 



The intestines are without caeca ; ^ the following are some 

 measurements : — 



Chloronerpes ywcatanensis . . . 8g inches 



Picus minor . . . . . .12 „ 



Xypoxanthus Bivolii . . . .12 „ 



Dryocopus martins . . . . 20 ,, „ 



The syrinx has no remarkable characters. It is quite 

 typically tracheo-bronchial with a pair of extrinsic and 

 a pair of intrinsic muscles. 



As to the shull, the woodpeckers have an unusual palatal 

 structure, which led Paekbr' to invent the term Sauro- 

 gnathous in order to express this peculiarity. The palatfe of 

 the woodpecker has, however, been variously interpreted. 

 Professor Huxley, in his paper on the bird's skull, directed 

 attention to an apparent vacuolation of the palatines, which 

 is illustrated in the accompanying figure (fig. 90) ; a slender 

 bar of bone passes backwards and comes into near relations 

 with an equally slender projection forwards of the palatine 

 bone, thus enclosing a space which in the fresh skull is filled 

 with membrane. The anterior process in the dried skull 

 is sometimes continuous (fig. 90), but sometimes not con- 

 tinuous with the ascending lamina of the palatine. Where 

 it is not continuous Professor Huxley found that its appa- 



' J. LiNDAHL, ' Some New Points in the Construction of the Tongue of Wood - 

 peckers,' Am. Nat. 1879, p. 43. 



' Exceptionally present in Oecimus viridis. 



" ' On the Morphology of the Skull in the Woodpeckers,' &c., Tr. Linn. Soc. 

 (2), i. 1875, p. 1. See also Kesslek, ' Zur Naturgeschichte der Spechte,' Bull. 

 Soc. Nat. Mosc. 1844, p. 285. 



