Genus NYCTIDROMUS, Gould.
C h a r a c t e r e s G e n e r i c i .
Rostrum mediocre, ad basin latissimum, hiatu amplissimo, rictu setis elongatis instructo. Nares sub-basales, elevates,
transversìm subovales, aperta. Alse mediocres, remige tertio caterisprastante. Cauda elongata, ampia, subrotmdata.
Tarsi nudi, elongati, antico sculettati. Digitorum externus et internus breves, intermedius elongatus, ungue pedinato ;
digitus posticus liber, parvus, et ungue parvulo instructus.
N Y C T ID R OM U S D E R B Y A N U S , Gould.
Nyct.fronte, vertice, nucM, et regione interscapulari cinerescentibus, minutissimt nigro pmctatis; vertice et nucha lined
irregulari nigrd ornatis; genis, plumis auricularibus, mentoque rufo-fuscis, lwc obscure! nigro fasciato, lined cervind ab
angulo oris; ala tedricibus rufo, cervino, nigroque ornatis; primariis ad basin nigrescentibus, rufo fasciatis, in medio
albis, ad apicem nigrescenti-fuscis; secondariis rufo fuscoque fasciatis ; scapularibus rufis, nigrescenti pmctatis et
lineatis necnon cervino-marginatis; dorso imo, redricibusque cauda duabus intermediis sordidi cervinis, nigr.o pun-
datis, et obscuri fasciatis; rectrice externd utrinque nigrd, inths albo marginatd; reliquis albis; corpore subtds cervino,
fusco fasciato ; pectore superiore plagd albd semi divisa ornato ; rostro pedib usque brunneis.
Long. tot. 12 m e .; rostri, 1-f-; ala, 7 ; cauda, 7 ; tarsi, 1-j-.
Forehead, top of the head, back of the neck, and space between the shoulders pale grey, minutely pencilled with
black, and with an irregular mark of black from the top of the head along the back of the n eck ; sides of the
face, ear-coverts, and chin rufous brown, the latter obscurely barred with black, a stripe of buff running from
the angle of the m outh; wing-coverts mottled rufous, buff and black, each feather largely tipped with buff;
base of the primaries black, banded with rufous, to which succeeds a central band of white, the remainder being
brownish b lack ; secondaries alternately with brown and rufous; scapularies rufous brown, freckled with
black, bounded externally with blackish brown, and margined with buff; lower p a rt of the back and central
tail-feathers dirty buff, obscurely freckled and barred with blackish brown; outer tail-feather on each side
black, with a white internal margin; the remaining tail-feathers white, under surface buff, barred with brown;
a white semidivided gorget across the chest; bill and feet brown.
Nydidromus Derby anus, Gould, in Proc. of Zool. Soc. Part VI. 1838.
T h e members o f this group are confined to South America; they run much on the ground, and are remarkable
for the great dilatation o f the base o f the under maxillary bones. There are a t least ten species o f this
peculiar form, among which has hitherto reigned the greatest confusion. The present bird, which I have
reason to believe has been confounded with other proximate species, I venture to distinguish by the title of
Derbyanus.
The figure is o f the natural size, and is taken from a fine example kindly lent to me by the Earl o f Derby.