. Bulletin of the British Museum (Natural History), Geology. HEADON BEDS OF ENGLAND 55 as Ml or M2 is uncertain; Mi has been distinguished here by a sHght anterior narrowing of the trigonid. The metaconid and protoconid are subequal (when unworn), opposite and transversely crested. The small though distinct low paraconid is median or slightly internal to the midline, forming the fairly sharp anterior apex of the tooth; a crest from this cusp meets the anterior protoconid crest. A fairly strong shelf-like antero-external cingulum is present. The hjrpoconid and entoconid are prominent and opposi
. Bulletin of the British Museum (Natural History), Geology. HEADON BEDS OF ENGLAND 55 as Ml or M2 is uncertain; Mi has been distinguished here by a sHght anterior narrowing of the trigonid. The metaconid and protoconid are subequal (when unworn), opposite and transversely crested. The small though distinct low paraconid is median or slightly internal to the midline, forming the fairly sharp anterior apex of the tooth; a crest from this cusp meets the anterior protoconid crest. A fairly strong shelf-like antero-external cingulum is present. The hjrpoconid and entoconid are prominent and opposite, the hypoconid being slightly larger; each cusp is united to the posterior trigonid wall by sharp crests. The hypoconulid is small, though distinct; it is strongly posterior to the hypoconid and entoconid, and posteriorly projecting; the cusp is usually slightly external to the midline and is joined to the hypoconid and entoconid by low crests. This condition is seen in the M3 of 36807, but this cusp in the M3 of 29718 and 36803 is distinct and median. The talonid is strongly basined. Small accessory crests and cuspules are variably developed in the molars: in 36803, 36807 and M25091, a discon- tinuous crest swings obliquely down the posterior trigonid wall from the metaconid towards the crista obliqua; this cannot be distinguished in other specimens owing to excessive wear. On M2 of 36807 and C54i62d, there is a small cuspule in the middle of the talonid at the base of the posterior trigonid wall. This is absent in C54i62b and C54162C. In other specimens wear is too great for this feature to be distinguished. The upper teeth are known only in the isolated state. C30713 and C30722, almost identical structurally, are the largest teeth; these are considered as M2. C54163 is somewhat smaller antero-posteriorly, showing several minor structural differences; this is tentatively considered as M^. C9677, markedly
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