Dr. Latham has very well described it, but quite overlooked the construction of the feet.
HALCYON collaris.
Collared Crabeater.
Generic Character.
Rostrum longissimum, rectum, validum, ad basin latius quam altius, lateribus tetragonis; mandibula superiore rectissima, ad basin rotundata; inferiore carinata, recurvata, margine superioris inferiorem obtegente. Nares basales, membrana tectæ, apertura nuda, lineari obliqua. Cauda plerumque mediocris. Pedes gressorii, digito antico interiore minimo aut nullo.