1885.] ON A TOOTH OF MASTODON LATIDENS. 777 



3. Description of a Tooth of Mastodon latidens, Clift, from 

 Borneo. By R. Lydekker, B.A., &c. 



[Eeceived August 18, 1885.] 



(Plate XLVIII.) 



The specimen forming the subject of the present notice was 

 forwarded from Borneo to the Secretary of this Society by Mr. A. H. 

 Everett, C.M.Z.S., who stated that it was found during the early 

 part of the present year by a Kadayan in the jungle in the vicinity 

 of Bruni, on the north-west coast of Borneo. Owing to the country 

 being in a disturbed state Mr. Everett could not visit the locality to 

 make further inquiries ; but there seems no doubt that the history 

 of the specimen is a true one. 



The specimen is the crown of the last left upper true molar of a 

 tetralophodont Mastodon, and agrees so closely with Indian teetli 

 of the Siwalik Mastodon latidens, Clift ^, that it may be safely 

 referred to that species, although it indicates a very small individual. 

 In mineralogical condition the specimen agrees very closely with 

 many Burmese specimens of the teeth of the same species, although its 

 colour is rather darker than is usually the case. The crown carries 

 five low transverse ridges, and a well-marked hind talon {ta') ; each 

 ridge extends straight across the crown, and the intervening valleys 

 are quite open and uninterrupted by accessory tubercles ; there is a 

 very small quantity of cement at the base of the hinder valleys. Eacli 

 ridge is divided into an inner and an outer moiety by a longitudinal 

 cleft, which is placed nearest to the outer border of the tooth. 

 The first two ridges are partially worn, and show dentine islets ; 

 the third is very slightly worn, but its enamel is not perforated ; 

 while the fourth and filth, together with the talon, are untouched ; 

 the third and fourth ridges show that there are four cusps on the 

 inner and two on the outer side of the longitudinal cleft. The inner 

 moieties of the first and second ridges present dentine islets with a 

 very imperfect trefoil shape ; and when more worn the islets of the 

 inner and outer moieties would unite and form transverse bands. 

 On the anterior aspect there is a disk caused by the pressure of an 

 adjacent molar, but the posterior aspect exhibits no such disk ; these 

 features, together with the characteristic shape of the crown and 

 the number of ridges, show that the tooth is the last of the true 

 molar series. 



Compared with the large series of Indian and Burmese teeth of 

 Mastodon latide7isii^j^ured by the present writer in the ' Palteontologia 

 Indica' (Mem. Geol. Surv. India 'J, the present specimen agrees 

 precisely in all general characters. The only other species to which 

 it presents any resemblance is the Indian M. perimensis, of which 

 characteristic teeth are figured in the same work ^ ; but it is 



1 Trans. Geol. Soc. ser. 2, vol. ii. pt. 3, p. 371 (1828). 

 - Ser. lU, vol. i. pis. xxxvii.-xxxix (1880). 

 ^ Vol. i. pis. xl., xlii., and vol. iii. pi. xvi. 



