PURBECK FORMATIONS. 31 



The projecting front teeth are made to catch, the canine and premolars to kill, the 

 molars to pierce and crush chitinous integument ; and, by the analogy of Moles, Shrews, 

 and Opossums of like size {Bidelpliys dorsigera, e. g., p. 105, fig. 22b), we may guess the 

 prey to have been Insects and other Annulosa. 



The mandibular dentition of this little marsupial ferine may be formularised as : — 



i- 4=14' "• \=^V P- 4=4' '«• 1=1 : = 32. 



The analogy of Myrmecobius checks any hasty conclusion as to there being precisely 

 as many teeth in the upper jaw as in the lower one of Amhlotherimn. 

 The dental formula of Mi/rmecobius is: — 



• Izif illJ ?ZI? ^nl P19 1 



«• 3_3> ^- \—\>P- 3—3' ^^' 6—6 ■ — 



The mandibidar dentition of AinpUtheriiim, is : — 



«• 3ZI. ^- \i:\>P- 6=6' ''"" 6=6 : = 32. 



The multicuspid character of the molars of Myrmecobius, and the almost uniform small 

 size of the cusps, are associated with a smaller relative size and a looser or more open 

 arrangement of the teeth than in Amblothenum. The affinity of AmUotlieriim to Amphi- 

 therium is closer than to Myrmecobius. The present species, Amb. soricinum, as repre- 

 sented by the mandible with the fuU adult complement of teeth, above described, is smaller 

 than any of the previously characterised species so represented. 



Species 2 — Amblotherium mustelula, Oioen. Plate II, fig. 2, 2a. 



The present specimen (PI. II, fig. 2, nat. size, and 2 a, magn. 3 diara.) agrees 

 generically in the character of the crown of the true molars (as exemplified by the tooth 

 marked m 3, in fig. 2 a) with the type of Amblotherium, and it presents the same 

 general configuration of the ascending branch and symphysial end of the jaw. The 

 difference of size is such as to lead me to regard it as specific, and this conclusion is 

 strengthened, if not confirmed, by modifications of shape and proportion of the hinder or 

 ascending portion of the ramus. 



The species Ambl. mustelula is represented by a right mandibular ramus, the inner 

 side exposed, showing five or six of the molary series in situ, but with crowns more or 

 less mutilated ; there are also some feeble indications of incisors. 



The jaw has a larger ascending branch and coronoid process than in Amb. soricinum 

 or in Amphitlierium ; remarkably larger than in Myrmecobius. The condyle ifi) projects 



' Waterhouse, "Description of a new Genus of Mammiferous Animals from Australia," &c., 'Trans. 

 Zool. See.,' vol. ii (1836), p. 149, pi. xxviii. 



