168 PROFESSOR OWEN ON THE OSTEOLOGY OF 



panse and flatness of the occiput occasioned by the more strongly developed lambdoidal 

 crest in the Pith. Satyrus ; and in the smaller relative as well as absolute size of the 

 ascending ramus of the lower jaw and of the condyles in Pith. Morio. The incisors 

 of the Morio, especially the large mid-pair above, are of equal size with those of the 

 Satyrus. The molar series in one of the male skulls (that in the British Museum) 

 occupy a longer tract in both upper and lower jaws than in the female Morio figured in 

 my previous Memoir'. 



In the lower jaw the dental series is uninterrupted in the skulls of both species of 

 Orang, the long and large crown of the upper canine diverging a little outwards as it 

 descends, and terminating outside the interspace between the crowns of the lower 

 canine and first premolar. 



In the skulls under comparison, the premolar and molar teeth are absolutely larger 

 in the smaller species of Orang. 



Pith. Morio. Pith. Satyrus. 



in. lines. in. lines. 



Extent of the molar series, above ... 2 4 2 1^ 



,, ,, ,, ,, below ... 2 8 2 6 



The bony palate is narrower and deeper in proportion to its length in the Pith. Morio. 

 The correspondence in the configuration and structure of the teeth in the two species 

 is very close. 



The differences between the skulls of the two Orangs, P. Satyrus and P. Morio, 

 besides those of size and proportion, which are noted in the "Table of Dimensions," 

 are chiefly as follows : — 



Concomitant upon the permanent retention of the characteristics of immaturity by the 

 adult male of the smaller species, to which ' arrest of development,' i. e. of development 

 in the Orang-direction, its more Human-like characters, are due, is the less produced tem- 

 poral ridge, and its separation from the one on the opposite side by a smooth convex tract 

 of cranium, 1 inch 10 lines in width at the narrowest part. To the same ' arrest ' are due 

 the more feeble and less outwardly arched zygomatic processes ; the lower and shorter 

 lambdoidal ridges, which are separated by the breadth of the posterior part of the space 

 dividing the temporal ridges, and a consequently more uniformly convex occiput. The 

 orbits are proportionally larger, and in one skull are more sharply defined. The shorter 

 and narrower pterygoid plates in the Pith. Morio relate to its proportionally smaller 

 mandible. The bony apertures, both external and internal, of the nasal or respiratory 

 passage are smaller in the Morio than in the Satyrus ; but the occipital foramen (/. mag- 

 num) in the skulls compared is relatively larger than in the Pith. Satyrus. 



The two skulls of the male Morio transmitted by Mr. Wallace present some notable 

 varieties, of which the most remarkable is that exhibited by the size and extent of the 

 molar teeth, especially those of the upper jaw. In the individual, however (no. 1), in 



' Trans. Zool. Soc. vol. ii. pi. 34. 



