Humero-sternal parts.-In one of the specimens of Saurian remains, presented by Colonel Birch to the Museum at Oxford, the humero-sternal, or rather humero-clavicular, parts on one side of the animal are almost perfect. It is only at the extremities of the clavicle and scapula that the bones themselves are preserved ; but the intermediate parts, though removed, have left an impression of their lower surface. Enough remains to enable us with certainty to identify these bones with more perfect specimens of the same, which have been found in a detached state. It is from these materials that I have effected the restoration of the humero-clavicular parts represented in Plate XLIX. fig. 2.
The humero-clavicular parts consist, as in birds, and as in the lizard and some other reptiles, 1st, of coracoid bones separated from the scapula ; 2d, of a small scapula; and 3d, of clavicles.
The coracoid bones in the specimen at Oxford, are greatly elongated in comparison of those represented in my first memoir, though resembling the latter in every other particular. I hesitate to consider this difference as specific ; because the shorter Coracoids evidently belonged to a much younger individual than the longer, as appears from the circumstance of these and other bones, which have become anchylosed in the latter case, remaining distinct in the former. I ought, however, to add, that a third fragment of this part, which certainly belonged to a large adult, and exhibits the anterior portion of the two Coracoids adhering to a series of anterior dorsal vertebra, agrees in form most nearly with the shorter specimen. The specimen belonging to the Duke of Buckingham possessed the long Coracoids, traces of them being very evident beneath all the anterior ribs. Should it appear on further inquiry, that there were two species, we learn from the specimens already procured, that the specific distinctions were very slight, that noticed in the Coracoids being in fact the only one that I have been able to detect after a careful collation of the most important parts in all the specimens that I have examined.
The scapula has been correctly represented in my first memoir; but the humerus, which I had there figured from the only specimen in which I had seen those two parts together, and which having belonged to the late Mr. Catcott, is preserved in the public library at Bristol, in consequence of an accidental dislocation, is exhibited in an inverted position. The clavicles consist of two transverse and one central piece. The former are the clavicles, strictly speaking ; the latter may perhaps more properly be referred to the sternum. The corresponding part or furcula in the ichthyosaurus also, consists of two transverse and one central piece, as docs that of the ornithorynchus, when young, as has been noticed by Mr. Clift; but the central piece in these animals