200 MERISTIC VARIATION. [part i. 



group of mammals of which I have been able to examine a con- 

 siderable number. In different collections 142 normal adult skulls 

 were seen and 12 cases of extra teeth. Of these one was a case 

 of extra incisor (Gorilla, No. 186), one of anomalous teeth (Gorilla, 

 No. 187), and the remainder molars. Thus far therefore there are 

 nearly 8 per cent, cases of extra teeth. This figure is remarkable 

 in comparison with the rarity of such cases in Hylobates (51 skulls 

 seen, all normal), and the like rarity in other Old World monkeys 

 (42-S normals and 2 cases of extra teeth). 



Simia satyrus (Orang-utan). 



Normal adult skulls seen, 52. 



Supern itinerary molars. 

 166. Adult male haying additional posterior molar (m 4 ) behind and 

 in series with the normal teeth, on both sides in upper jaws and on 

 left side in lower jaw. In each case the in 4 is rather smaller than 

 ??i 3 , but all are well formed, having each four cusps and the normal 

 complement of fangs, viz., one in front and one behind in the 

 lower jaw, and two on outer and one on inner side in upper jaw. 

 On right side of lower jaw there is no trace of additional molar, 

 though there is almost as much room for it as on the left side. 

 C. M., 1160, D, described by Humphry, G. M., Jour. Anat. Phys., 

 1874, p. 140, Plate. 



16/. Female (Borneo) having six cheek-teeth in each upper jaw and in 

 right lower jaw [doubtless a case like the foregoing] mentioned by 

 Peters, W., Sitzungsb. naturf. Fr. Berlin, 1872, p. 76. 



1G8. Specimen with large alveolus on each side for w\ L. M., 24. 



169. Specimen (Borneo) having m 4 in right lower jaw, behind and in 

 series with the normal teeth. The tooth is of rather small size, but is 

 regular in position and form. B. M., 3, m. 



170. Specimen having a right ^ more than half the size of m :i - U. C. M., 

 E, 253. 



171. Specimen having supernumerary molar on each side in lower jaw. 

 Mayer, Arch. f. Nature/., 1849, 1. xv. p. 356. 



172. Similar case. Fitzinger, Sitzungsb. math. — nat. CI. Ak. Wien, 

 1853, i. p. 436. 



Similar case. Bruhl, Zar Kenntniss des Orangkopfes, Wien, 1856. 

 [] refers to the case described by Fitzinger.] 



Molar absent. 



173. Specimen "remarkable for absence of the upper right third 

 molar and for absence of nasal bones, which are greatly reduced 

 in some other specimens." C. S. M., 44. See Catalogue Mus. Coll. 

 Surg. 1884. The other teeth are all normal and fully formed. 



Variations in position of teeth. Though not directly pertaining 

 to the subject here considered, the following examples of consider- 



