PURBECK PORMATIONS. 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 {Bidelphys dorsigera, e. g., p. 105, fig. 22b), we may guess the 

 prey to have been Insects and other Annulosa. 



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



i- 4=4' ""' 1=1' P- 4=4' '"^•7=7: = 32. 



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

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

 The dental formula of Myrmecohius is: — 



• Izif liz} 3—3 5— 5 

 «• z^V ^' 1— 1'-^-3— 3' ''^^' 6—6 



The mandibular dentition of Anvpldtherium is : — 



^^ = 52.1 



«• 3_3. ^- i—i>P' 6— 6» ^' 6—6 : = 32. 



The multicuspid character of the molars of Myrmecohius, 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 Amhlotherium. The affinity of Amhlotherium to AmpM- 

 therium is closer than to Myrmecohius. The present species, Amh. soricinum, as repre- 

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

 than any of the previously characterised species so represented. 



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



The present specimen (PI. II, fig. 2, nat. size, and 2 a, magn. 3 diam.) 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 Amhlotherium, 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 Amhl. 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 Amh. soricinum 

 or in Amphitherium ; remarkably larger than in Myrmecohius. The condyle {h) projects 



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

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



