Genus — A C E L O . 
Bacelo Leach, Zool. Miscell., Vol. II., p. 125, 1815 
Type D. giga^. 
Parakyon Gloger, in Froriep’s Notizen, Vol. XVI., 1827, 
j)* 278. B. •• .. .. .. .. 
Agreutes Billberg, Synops. Faunae Scand., tab. A, 1828 
Choucalcyon Lesson, Traite d’Ornith., p. 243, 1830. 
Aleo spelt — 
Ghonalcyon Gray, Genera Birds, Vol. 1., p. 77, 1846. 
Choacalcyon, id.. Cat. Gen. Subgen. Birds, p. 1.5, 1855. 
Nycticeyx Gloger, Hand. u. Hilfsb. Naturg., p. 338, 1842. 
Type D. gigas. 
Type D. gigas. 
Type D. gigas. 
Type D. gigas. 
Largest Dacelonine birds, with long, massive bills, long wings, short tails, 
and small legs and feet with four toes. The bill is long, broadly triangular, tip 
narrowly attenuate and slightly descending, but not forming a hook, while 
a sinus succeeds the tip, the mandible edges thence straight and entire. The 
culmen is keeled, sides straight not curved. The nostrils are small slits 
placed at base of bill midway between culmen and mandible edges; these 
are more open than in the preceding family. The lower mandible is broad 
at base, gonys at posterior two-thirds, thence ascending ; rami short, interramal 
space feathered. 
The wing has the first primary shorter than the sixth, the intervening 
four subequal, the third and fourth longest. The tail is long, almost two-thirds 
the length of the wing : it is round, not much graduated, the outer two feathers 
shorter than the others, but not to a great extent. The feet are small. The 
very short tarsus is reticulate throughout, the reticulations very fine behind : 
the inner toe is longer than the tarsus, and also the hind toe, but shorter than 
the outer, which is subequal to the middle toe. The middle claw is very long. 
This is the type genus of the Bacelonidse, and the sexes are alike, while there 
is an ill-defined crest present. Consequently, whether the succeeding Australian 
genera are truly referable to this family the present species must be. I would 
again quote Miller : “ The natural grouping of the genera in the Baeeloninae 
is a matter of considerable difficulty, and no arrangement can be considered 
final until the internal anatomy has been examined.” 
These large species have been already subdivided and the name Dacelo 
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