The bony structure of the head is remarkable on account of its massive and thick proportions; the skull itself is strongly enlarged posteriorly, and the temporal fossae are bordered by very pronounced ridges, especially those on the occipital region. The upper side of the skull is hardly convex, and the interorbital region is large, but only slightly depressed along its middle line. The bill is stout, almost straight, a good deal enlarged at its base and rounded beneath. The nostrils are large and preceded by a large groove, which extends very far towards the tip.

It is impossible to confound this skull with that of any Bittern, the latter having the beak relatively slender and only barely exceeding the skull in length. These also have the skull much constricted at the temporal region. The fossil skull from Rodriguez therefore presents characters essentially those of a Heron, but differs from all known species in its massive appearance. In the Grey, Purple and Goliath Herons, as well as in the Egrettes, the head is narrower, more elongated, the bill less conical and less strong. In Ardea atricollis, now inhabiting Madagascar, the beak much resembles that of our extinct species, but it is longer and less enlarged at the base. The interorbital area is much wider, while on the other hand the hinder portion of the skull is narrower and more elongated, which gives to the skull a totally different aspect.

The feet relatively to the head are extremely short, and from this I conclude that we know no species of Heron which can be compared to that of Rodriguez. Nevertheless, the tarso-metatarsus presents all the characters

of Ardea, and is far removed from that of Botaurus. The tibia is big and short; it surpasses in length the tarso-metatarsus by about a third, as is usual in the Herons; but the femur on the contrary is strongly developed, being quite as large as in the Ardea cinerea; which shows us that the body of this creature was of large size, and that the reduction in size of the feet had only taken place at their extremities.

The sternum is puny and small as compared with the creature's size. It is clearly that of a bird not furnished with powerful wings, and is even much less elongated than in the Bittern, but the coracoidal bones are very long and slender. The wings also were short and feeble, the humerus being hardly as big as in Butorides atricapilla. It is conspicuously slenderer and shorter than in the Bittern. The main body of the bone is slightly curved on the outside, and the lower articular condyle is large and flattened. I have not been able to examine any bone of the "manus," but the metacarpal bone shows exactly the same proportions for the wing as does the humerus, as it also barely reaches the size of that of Butorides atricapilla. The measurements are as follows:—

Skull.
Total length 154 mm.
Length of upper mandible 94 "
Width of upper mandible at base 22 "
Width of interorbital region 22 "
Space between the mastoid apophyses 40 "
Width of skull at level of postorbital apophyses 40 "
Length of lower mandible 147 "
Tarso-metatarsus.
Total length 95-162 mm.
Width at proximal extremity 14 "
Width at distal extremity 13.5-14 "
Width of shaft 6.2-7 "
Tibio-tarsus.
Total length 140-210 mm.
Width at distal extremity 12-13 "
Width at proximal extremity 13-14 "
Width of shaft 6-6.5 "
Femur.
Total length 90-92 mm.
Width of distal extremity 15-16 "
Width of proximal extremity 14-16 "
Width of shaft 6.2-7 "
Sternum.
Total length 64-88 mm.
Width in front 35-48 "
Width behind costal facets 26-36 "
Width at posterior border 27-35 "
Coracoidals.
Total length 59-67 mm.
Width at lower extremity 17-18 "
Humerus.
Total length 118-180 mm.
Width of proximal extremity 20-27 "
Width of distal extremity 16.5-24 "
Width of shaft 7-11 "
Metacarpals.
Total length 62-98 mm.
Width of proximal extremity 12-17 "
Width of distal extremity 7-11 " "

The anonymous author of the manuscript "Rélation de l'île Rodrigue" (see Ann. Sci. Nat. (6) II p. 133 et seq. 1875) about the year 1830 mentions this bird as follows:—"There are not a few Bitterns which are birds which only fly a very little, and run uncommonly well when they are chased. They are of the size of an Egret and something like them."

Habitat: Rodriguez Island.

2 Humeri, 2 Femora, 2 Tibiae, and 2 Metatarsi in the Tring Museum.