174 PROFESSOR OWEN ON THE OSTEOLOGY OF 



maxillaries, with concomitant varieties of profile contour, — offering forms and characters 

 of cranium intermediate between the two extremes of the crested adult male skulls 

 figured in the Zoological Transactions, vol. i. pi. 54, and vol. ii. pi. 32. 



I next proceed to notice some characters in the series of six adult male skulls of the 

 large Bornean Orang, which have no parietal crest. 



In the youngest of this series, no. 1100, the temporal ridges are 14 lines apart, yet 

 half the crowns of the incisors are worn away ; but the crowns of the canines are nearly 

 entire, and the molars are not more abraded than in the crested skull, no. 3 B. The 

 lambdoidal ridges are interrupted by the breadth of the space between the temporal 

 ridges. 



In the skull no. 1101 (PL L. fig. 3), those ridges are 10 hues apart, and are more 

 directly continued behind into the lambdoidal ridges : the inner halves of the upper 

 molars (fig. 4) and the outer halves of the lower molars are worn into smooth cavities. 

 There are styloid processes 3 lines in length. 



In no. 1086, with the molars as much worn as in the preceding skull, the temporal 

 ridges are 12 lines apart : there is a low smooth longitudinal rising, not to be called a 

 ridge, in the midspace between the ridges. The styloid processes are 3 lines in length. 

 The lower molars of this skull are figured in Plate L. fig. 5. 



In no. 1087, the temporal ridges are 10 lines apart, with a low narrow median longi- 

 tudinal rising; the molars are as much worn as in no. 1101, except that the last, owing 

 to their unusually small size, have escaped their due share of abrasion. One half of the 

 crowns of the canines are worn down : the lambdoidal ridge is strongly developed, and 

 the occiput proportionally broad. 



In no. 1 131, the grinders are so much worn that the roots protrude from the sockets, 

 yet the temporal ridges are 6 lines apart. 



A still greater degree of abrasion is shown by the molars of no. 15, the inner halves 

 of the upper ones being ground down to the roots, which project from the sockets : the 

 temporal ridges are 3 lines apart. 



The kind and degree of variety in the above series of non-crested skulls are the same 

 as in the crested series. My interpretation of the difference of development of the 

 temporal muscles, as indicated by the separation or confluence of the temporal ridges 

 in these great Orangs, is as follows : — those muscles are closely related, in regard to 

 their development beyond a certain size, to the magnitude and use of the canine teeth. 

 The great proportional size of these teeth is a characteristic of the male sex ; their 

 chief use has probably, therefore, a sexual relation. Like the horns of the Bull or the 

 antlers of the Deer, they are the weapons by which the males contend for the possession 

 of the female. 



Orangs may be born with original differences of disposition, some being more 

 courageous, more combative than others. This proneness to fight and conquer is the 

 probable concomitant of a superior general robustness of frame, of greater nervous 



