276 On a Double-rooted Tooth from the Purheck Beds, 



canine," and it is subsequently added that the canine is " a 

 powerful tooth implanted by two stout fangs." The tooth 

 as figured (Journ. Acad. Nat. Sci. Philad. 2nd ser. vol. ix. 

 pi. ix. fig. 4) does not bear out the alleged double- rooted 

 character. I have accordingly made an enlarged drawing of 

 this tooth, so as to compare with the tooth of Nuthetes. It is 

 exposed on the inner side ; the crown is enamelled at its 

 summit, with ridges and a slight cinguloid thickening at the 

 base of the enamel ; the extremity of the root of the tooth is 

 lost. I have no doubt it is channelled in the way Professor 

 Osborn's figure indicates ; but, from the impression left where 

 the anterior angle of the root is lost, which appears to be that 

 of the external surface of the jaw, I cannot regard it as better 

 evidence of a divided root for that particular tooth, than the 

 corresponding impression of a tooth of Nuthetes, already re- 

 ferred to, would give for division of the roots in that specimen. 

 There is a similar pit to that figured by Owen in Nuthetes 

 apparently, on the external side, and a compression of the 

 part of the root beyond it. In any case the evidence is not 

 conclusive that the root was divided in this tooth of Trico- 

 7iodon ferox, which is the only example available for exami- 

 nation in this country. If the fossil gave such evidence, 

 then the roots indicated would be dissimilar in form to those 

 figured in the fossil tooth in the British Museum, No. 48,208. 

 It is possible that a nearer comparison with the crown of that 

 fossil might be found in Plac/iaidax medius (Owen), but no 

 one has yet affirmed that the roots of the tooth are divided in 

 that genus. 



It was from considerations of this kind that I judged, 

 when originally comparing the specimen with the teeth 

 of Purbeck Mammalia, that there vvas no sufficient ground 

 for discussing the question of it being possibly mam- 

 malian. And now, having figured the evidence for such a 

 comparison, it must be left to future discovery to determine 

 whether the tooth, which has the mammalian character of 

 two roots, can be identified as a Mammal, or whetlier it must 

 still be regarded as an abnormal form of a tooth of JSIuthetes 

 destructor. If the evidence for the double-rooted canine in 

 the Purbeck mammals remains no stronger than I have re- 

 corded, then the weight of evidence is against the suggested 

 mammalian interpretation ; but the resemblance in tlie form 

 of the crown in these two types of teeth is sufficient to make 

 further evidence desirable of the root character in those mam- 

 mals, before the tooth which has hitherto passed unchallenged 

 as Nuthetes is accepted unreservedly as a reptile-tooth which 

 has abnormally developed a divided root. 



