460 



2545. The skull of a male Malayan Dugong (Halicore indicus}. 



The incisive tusks are protruded and bevelled off obliquely from their outer side, and their 

 sockets have the parietes entire, as is usual in this sex. The molar teeth are reduced to two 

 on each side of both jaws. A small rudimental incisor is retained in the third socket, counting 

 from below upwards, of the left side, lower jaw. The otosteals and the tympanic portion of 

 the petrotympanic of the left side are wanting. 



Presented by Hugh Cuminy, Esq. 



2546. The mutilated skull of a male Malayan Dugong (Halicore indicus). 



The molar teeth are reduced to three in number on each side of both jaws. The outer 

 parietes of the alveolus of the permanent incisive teeth of the upper jaw are entire. The 

 basi- and ex-occipital bones are wanting. 



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



2547. The mutilated skull of a female Malayan Dugong (Halicore indicus). 



The molar teeth are reduced to three on each side of both jaws : the anterior one will be 

 seen to be relatively smaller than in the female Australian Dugong (No. 2634) of corresponding 

 age. The right alveolus of the upper incisor is laid open, and the tooth exposed ; it has been 

 bisected longitudinally, and shows the small size and depth of the conical cavity for the pulp 

 at its base. The summit of the last molar, left side of the lower jaw, has been removed, and 

 the surface polished, showing the dentine and the thick surrounding layer of cement. The 

 right squamosal has been removed, together with the petrotympanic bone, showing the loose 

 manner in which the latter is lodged in the smooth cavity ; a fracture of the squamosal 

 exposes the dense texture of the bone. 



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



2548. The skull of a young male Malayan Dugong (Halicore indicus), vertically and 

 longitudinally bisected. 



It shows the thickness and dense structure of the cranial walls. The sockets of the deci- 

 duous and permanent incisor and molar teeth are displayed in the left moiety. The deciduous 

 incisor of the upper jaw was attached chiefly to the thick and callous gum covering the 

 extremity of the premaxillary : its shallow socket is situated anterior to the lower extremity 

 of that of the permanent incisive tusk : this has not yet been protruded : a longitudinal sec- 

 tion has been removed from it, exposing its deep pulp-cavity with a widely open base. 



This skull exemplifies the period when the molar series of teeth may be viewed in their most 

 complete state. Not more than twenty molar teeth are developed in the present species of 

 Dugong, viz. five on each side of both upper and lower jaws : but these are not in use at the 

 same time, the first being shed before the last has cut the gum. The molar teeth increase 

 very regularly in size ; the fang of the first and that of the second is soon completed and 

 solidified ; that of the third is more elongated, and retains its basal cavity longer, but it 

 becomes at length contracted to a point, solidified, partially absorbed, and the tooth is then 



