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Show 1867.] PROF. ALLMAN ON POTAMOGALE VELOX. 257 formula of this animal as given by Prof. J. V. Barboza du Bocage * and that in the formula given by myself, the Lisbon zoologist describing ten teeth on each side in both jaws, while in m y specimen only nine were apparent on each side. Mr. Mivart, however, thought that he saw indications of a tooth still confined within the mandible at the extreme posterior end of each ramus, while a small, apparently fractured, surface in tbe corresponding part of the maxilla appeared to afford evidence of a portion of the upper alveolar margin with its tooth having been here carried away. I have now the satisfaction of being able to confirm in great part the suspicion of M r . Mivart. In the case of the mandible, it was easy enough to set the question at rest. On removing a portion of the side of the mandible, where the missing tooth was supposed to be concealed, a small cavity was exposed, in which, with some care, a minute calcareous point, the commencing calcification of the dental papilla, still enveloped in the remains of its capsule, was detected. There can thus be no doubt of the presence of a rudimental tooth on each side in the mandible of m y specimen, behind the most posterior of those previously described by me. Of the existence of a corresponding tooth in the maxilla, no such direct evidence can be adduced. There is certainly a very small rough surface at the most posterior end of the alveolar margin at each side, and I agree with Mr. Mivart in thinking it probable that a portion of this margin has been here broken off; the missing fragment, however, must have been extremely small, and the tooth which it contained must have been in at least as rudimental a state as that of the mandible. Had I become acquainted with Prof. D u Bocage's determination of the dental characters of Potamogale before m y own communication had been printed, I should perhaps have made a search in the same direction for the missing teeth; but as it was, m y specimen gave m e no reason to suspect that it did not offer an exposition of the complete series, though it is now plain that it had not yet developed its last molars. The facts now stated render necessary a correction of the formula which I had already given as that of the teeth of Potamogale, and which must henceforth be regarded as applying to the dentition of this genus before the adult state had been attained in the development of the last molars. In the corrected formula the incisors and premolars must remain as before, but to the true molars one must now be added. The dental formula, as amended for the adult, will accordingly stand as follows :- Lg. C.t!. F.fE*. M.g = 40. PS. Since the above note was communicated to the Society, I have been enabled, through the kindness of M . Jules Verreaux, of * Noticia acerca los Caracteres e Affinidades Naturaes de un novo Genero de Mammiferos Insectivoros. Lisboa, 1865. PROC. ZOOL. Soc-1867, No. XVII. |