At the very beginning of the year 1832 Cuvier laid before the Academy of Sciences of Paris a memoir on the progress of ossifi cation in the sternum of birds, of which memoir an cuvier abstract will be found in the Annales des sciences and naturelles (xxv.
Detail, illustrating his statements by the preparations he exhibited, the progress of ossification in the sternum of the fowl and of the duck, pointing out how it differed in each, and giving his interpretation of the differences.
The most novel feature, and one the importance of which most ornithologists of the present day are fully prepared to admit, is the separation of the class A y es into two great divisions, which from one of the most obvious distinctions they present were called by its author Carinatae' and Ratitae, 2 according as the sternum possesses a keel (crista in the phraseology of many anatomists) or not.
It is in fact doubtful whether the so-called sternum of batrachians, in most cases a mere plate of cartilage, has been correctly identified as such.
But it was now made to appear that the struthious birds in this respect resembled, not only the duck, but a great many other groups - waders, birds-of-prey, pigeons, passerines and perhaps all birds not gallinaceous - so that, according to Cuvier's view, the five points of ossification observed in the Gallinae, instead of exhibiting the normal process, exhibited one quite exceptional, and that in all other birds, so far as he had been enabled to investigate the matter, ossification of the sternum began at two points only, situated near the anterior upper margin of the side of the sternum, and gradually crept towards the keel, into which it presently extended; and, though he allowed the appearance of detached portions of calcareous matter at the base of the still cartilaginous keel in ducks at a certain age, he seemed to consider this an individual peculiarity.
The median and posterior extension of the body of the sternum is a direct outgrowth of the latter, therefore FIG.
De Castelnau's Expedition dans les parties centrales de l'Amerique du Sud some important memoirs describing the anatomy of the hoactzin and certain other birds of doubtful or anomal ous position, published some remarks on the characters which could be drawn from the sternum of birds (Ann.
It was only when, after a close examination of the sternal apparatus of one hundred and thirty species, which he carefully described, that he arrived (pp. 177-183) at the conclusion - astonishing to us who know of L'Herminier's previous results - that the sternum of birds cannot be used as a help to their classification on account of the egregious anomalies that would follow the proceeding - such anomalies, for instance, as the separation of Cypselus from Hirundo and its alliance with Trochilus, and the grouping of Hirundo and Fringilla together.
Be that as it may, he declares that characters drawn from the sternum or the pelvis - hitherto deemed to be, next to the bones of the head, the most important portions of the bird's framework - are scarcely worth more, from a classificatory point of view, than characters drawn from the bill or the legs; while pterylological considerations, together with many others to which some systematists had attached more or less importance, can only assist, and apparently must never be taken to control, the force of evidence furnished by this bone of all bones - the anterior palatal.
L'Herminier arrived at the conclusion that, so far from there being only two or three different modes by which the process of ossification in the sternum is carried out, the number of different modes is very considerable - almost each natural group of birds having its own.