AXIAL SKELETON OF THE PELECANIDZ. 
oo 
Or 
oo 
THE STERNUM. 
The sternum (Plate LXI. figs. 3 & 4) is shorter and broader than in Sula, with the 
proportions of Pelecanus, but less contracting, laterally, postaxiad. The clavicles are 
not ankylosed to it. 
The keel extends much relatively as in Pelecanus; and the coracoid grooves form an 
angle much as in that genus, and therefore a less acute one than in Sula. The median 
xiphoid (mx) agrees with that of Su/a in not extending postaxiad as much as the lateral 
xiphoids do, thus differing from Pelecanus. These lateral xiphoids are obtusely pointed, 
not spatulate (lz). 
The pleurosteon may have only four elongated articular processes in Ph. carbo, but 
generally has five such in other species. 
The concavity and convexity of the sternal osseous sheet is much as in Pelecanus, 
and not flattened as in Sula, though the middle part of the postaxial portion of its 
ventral surface is not so convex transversely as in Pelecanus. 
The articular surface behind the coracoid groove is not so broad relatively as either 
in Sula or Pelecanus. 
A process may spring preaxiad from dorsal end of concave dorso-preaxial margin 
of keel. 
PLOTUS. 
The anatomy of Plotus has been recently described by Professor Garrod, in a very 
interesting and instructive memoir in the ‘Proceedings’ of the Zoological Society 
for 1876, p. 335, pls. 26 to 28. Its skeleton was noticed by Mr. Eyton in his 
‘Osteologia Avium, p. 218; and by W. Donitz (as concerns the cervical vertebre) 
in the ‘Archiv fiir Anatomie und Physiologie,’ 1873, p. 357, plate ix. a. 
It has been described with much detail by Brandt, who has given figures of the entire 
skeleton, the pelvis, and sternum, in the ‘Mémoires de l’Académie des Sciences de 
St.-Pétersbourg,’ 6™° serie, Sciences Mathématiques, Physiques et Naturelles, tome v. 
seconde partie, Sciences Naturelles, tome iii. 1840, p. 132, pl. 4. 
I have myself examined a skeleton of Plotus anhinga in my own collection, and also 
another and a skeleton of P. nove-hollandie, both in the Museum of the Royal College 
of Surgeons. 
The total number of vertebre seems to be 45 or 46, without counting the pygostyle. 
These vertebre are subdivisible as follows—18 cervical vertebra (in the specimen 
of P. nove-hollandie there are only 17; but this is probably owing to one vertebra, 
the 15th, having been lost), 2 cervico-dorsal, 5 or 6 dorsal (in one specimen of P. 
anhinga there are but 5), 4 lumbar, 2 or 3 lumbo-sacral, 2 sacral, 4 sacro-caudal, and 
7 or 8 caudal vertebre. 
