APPENDIX. 329 



the " Philosophical Transactions/' 1821, plate XX, as it is 

 in the largest and oldest individuals. The neck of the 

 scapula is relatively longer, and the coracoid process rela- 

 tively broader and shorter in the Halicore australis than 

 in the Halicore indicus. 



The lower jaw of the younger specimen of Halicore 

 Australis shews, by the superior size and depth of the 

 third incisive alveolus, counting from below upward, in 

 each ramus, that the rudimental incisors were present in 

 those sockets, where they have been commonly found in 

 the Halicore indicus. In the lower jaw of the older 

 specimen of Hal. australis these sockets were filled up, 

 like the rest, by a coarse reticulate bony mass. 



Of several upper permanent incisive tusks transmitted 

 by Mr. Jukes from the North Coast of Australia one pair 

 shews the deflected shallow base, marked off from the body 

 of the tooth, as in the incisive tusks of the female Halicore 

 indicus; these female tusks in the Australian Dugong 

 were each 7 inches long.* Other tusks of equal length, 

 with an unexpanded and unbent base, more deeply exca- 

 vated for the persistent pulp, as in the incisive tusks of the 

 male Halicore indicus, shew the same unworn, rough, sub- 

 obtuse apex as the female tusks, and indicate that these in- 

 cisive tusks had not been protruded and put to use, as we 

 find those of similar size in the males of the Halicore indi- 

 cus to have been, when they always shew an obliquely worn 

 or bevelled extremity as well as the unexpanded hollow 

 base. The correspondimg base of the apparently male tusks 

 in Halicore australis are less deeply excavated than those 

 of the male Halicore indicus. 



The chief specific character of the Australian Dugong 



* For the determination of the sexual characters of the tusks of the 

 Dugong, see my 'Odontography,' p. 364. 



