459 



Order SIRENIA. (CETACEA HERBIVORA, Cuvier.) 



Genus Halicore. 



2543. The skeleton of a female Malayan Dugong (Halicore indicus). 



The tusks are full-grown, exserted, and slightly abraded outside the point ; the base of the 

 socket is open externally and exposes the pulp-cavity of the tusk. The molars are reduced 

 to the last two on each side of both jaws. The pleurapophyses of the second, third, sixth 

 and seventh cervical vertebrae have remained unossified, leaving an open notch for the verte- 

 bral artery. The neurapophyses of the sixth and seventh cervicals are unanchylosed above. 

 There are 19 dorsal vertebrae, but the nineteenth pair of ribs are much shorter, straighter, 

 and more slender than in the rest, and illustrate the nature of the transverse processes 

 of the succeeding vertebrae, which are short and straight anchylosed ribs. The spinous 

 processes rapidly increase in length from the last cervical to the fourth dorsal, and continue 

 of equal length to near the middle of the tail. The iliac portion of the pelvic bones is 

 shorter, and the ischial portion longer, than in the Australian Dugong (No. 2632). The 

 first pair of hsemapophyses, here preserved, are long, distinct from each other, and are arti- 

 culated to the interspace between the sixth and seventh vertebrae, counting from the dorsal : 

 the same elements forming, by the confluence of their lower ends, the ' chevron-bones,' are 

 articulated to the interspaces of the succeeding vertebras as far as the nineteenth: the 

 depressed terminal caudal vertebrae are wanting in this skeleton. A strong process is 

 developed from the under part of the neck of the first rib. The distal epiphysis of the 

 humerus has coalesced with the shaft, but those of the radius and ulna remain distinct. The 

 first row of carpal bones consists of two, one articulated to the radius, the other to the 

 ulna and fifth digit, and both to the single bone representing the second row. The first digit 

 consists of a short metacarpal, the others have supported three phalanges. 



Presented by Sir TJiomas Stamford Raffles, P.Z.S. 



2544. The skeleton of a young female Malayan Dugong (Halicore indicus). 



The deciduous incisors of the upper jaw are present in their alveoli, but do not project be- 

 yond the surface. The germs of their successors are seen by a breach of the premaxillary 

 bone. There are four alveoli on each side in the anterior, sloping, truncated part of the lower 

 jaw ; these are destitute of teeth. In the maxillary bones there are four open alveoli on each 

 side, and one other closed, save where a very small aperture displays the germ of the tooth 

 within. The molar series of the lower jaw presents a similar condition. There are 7 cervical 

 vertebrae, the atlas and axis being separate. Besides these there are 56 vertebrae, nineteen of 

 which support moveable ribs, and four pairs of these join the sternum : the three following 

 have transverse processes joined by suture to the centrum. The thirty-second vertebra begins 

 to have haemapophyses. The first thirty-two vertebrae have their neurapophyses united by 

 suture to their respective centrums. 



Presented by Sir Thomas Stamford Raffles, P.Z.S. 



3N2 



