In the direction of the ectolateral processes _Goura_ (ib. fig. 3, _h_) is intermediate between _Didunculus_ and _Didus_. The pectoral ridge on the outer surface of the sternum, continued backward from the outer end of the coracoid groove, is adaptively better marked in Pigeons of flight than in the Dodo; and the pair of ridges are more nearly parallel in their backward course, not so convergent as in _Didus_. In _Goura_ the subcostal ridge is better marked than in _Didunculus_. In no Dove of flight is the body of the sternum so broad and hollow as in _Didus_ (Pl. XI. fig. 4); in this respect the Vulture more nearly resembles the Dodo, as it does also in the more convex anterior contour of the keel: but the vulturine sternum does not lose breadth as it extends backward; it is a square-shaped shield in birds of prey, shorter in proportion to its breadth, with a greater extent of costal process and margin, and with the ectolateral processes, when they exist, extending backward as far as the hinder border of the bone. In the thorough quest of resemblances to the Dodo’s sternum which I have made through the class of Birds, I came upon an unexpected superficial likeness to it in the sternum of a Night-jar (_Podargus humeralis_). The ectolateral processes (Pl. XII. fig. 4, _h_) rise behind the moderately extended costal borders, _c_; and beyond them the body of the sternum converges to an obtuse end, with a contour similar to that in _Didus_. Moreover the coracoid grooves are divided from each other by a free concave border, less deep and extensive, indeed, than in _Didus_, but as free from any trace of episternal projection. The ectolateral processes, however, are extended backward to beyond the sternal body; and this part usually shows a pair of small entolateral notches, _f′_, of which one was present on one side in the specimen figured. Through the reduction of the coracoids in all flightless birds, there is an interval between their sternal articulations: this is long and concave in the Dodo, but is longest and most deeply concave in _Apteryx_; it is long but almost straight in _Rhea_; in _Casuarius_ and _Dromaius_ it is narrow but deeply notched; in _Struthio_ it developes a short episternal process. In no Grallatorial sternum with both ecto- and ento-lateral processes (as e.g. _Otis_, _Œdicnemus_, _Charadrius_) do the former project, as in _Didus_ and the Rasores, immediately behind the costal margin, but they are continued, parallel with the keel, from the outer and posterior angle of the sternum, distant from the costal margin. In old Plovers the entolateral process joins the contiguous angle of the sternal body, and converts the inner notch into a foramen.