its whole configuration, notably by the shape and position of the precoracoid process, the various articulating facets at the dorsal end, and the prominent lip on the visceral or internal surface of the median portion of the sternal articulating facet." The following are the measurements:-- Length of ulna 111-112 mm. Length of metatarsus 81- 87 " Length of coracoid 48 " Habitat: Mauritius. Although _megacephala_ and _mauritiana_ have been placed in _Ardea_ and _Butorides_ respectively, from the short, stout legs and general build, I am inclined to think that all three of these Herons belong to the genus _Nycticorax_. {117} PROSOBONIA BP. This genus is, in the Catalogue of Birds, placed in a section with somewhat long tarsus, the latter being longer than the culmen, containing in addition to _Prosobonia_ the genera _Tringites_, and _Aechmorhynchus_ (see afterwards), and it differs from the latter by its long hind toe, from the former by its square tail. The position of this singular bird is, however, not quite certain. The late Henry Seebohm placed it in the genus _Phegornis_, though the latter has no hind toe whatever, and it has even--but doubtless wrongly--been suggested that it belonged to the _Rallidae_, rather than to the _Charadriidae_. We know only one species. It is true that Dr. Sharpe bestowed a new name on the figure of Ellis, which is said to have been taken from an Eimeo-specimen, but it is hardly creditable that it belongs to a different species. Latham appears to have had three specimens, which were all three different from each other. Both Forster and Ellis, in their unpublished drawings in the British Museum, as well as Latham, evidently considered all three to belong to the same species, and it is not advisable now to over-rule their verdict, given with the specimens before them, merely on account of the different plumages, since we all know that most waders, and especially brightly-coloured ones, differ considerably in plumage, according to age and seasons. We are convinced that "_P. ellisi_" has been a younger bird. Sharpe attaches importance to the different habitat, but this is no argument in this instance, because Eimeo is, at the nearest point, not more than seven and a half miles from Tahiti,[2] and it is quite against all precedents among _Charadriidae_ and beyond all plausibility that two such closely situated islands have closely allied forms of a Wader. {118} PROSOBONIA LEUCOPTERA (GM.) (PLATE 35.) _White-winged Sandpiper_ Latham, Gen. Syn. III, pt. 1, p. 172, pl. LXXXII (1785--Otaheite and Eimeo). _Tringa leucoptera_ Gmelin, Syst. Nat. I, p. 678 (1788--ex Latham!); Westermann, Bijdr. Dierk. I, p. 51, pl. 15 (1854--Figure of the type). _Totanus leucopterus_ Vieillot, Nouv. Dict. d'Hist. Nat. (Ed. II) VI, p. 396 (1817).