モグラ屬の下顎犬齒と稱せらるるものは下顎第1前臼齒なり
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概要
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Talpinae, the family of the moles, consists of two genera, Talpa(European mole)and Mogera(Japanese mole, also Formosan, Corean, Manchurian and Chinese moles). The Talpa europaea Linnaeus is the typical animal of them. About shape and numbers of upper teeth we could not find any difference between Talpa europaea and Mogera but there is a little difference in the lower, finding twenty two teeth in Talpa europaea and twenty in Mogera. Therefore, in the lower jaw, Mogera lost two teeth in number also at the premolar portion by reason of various authors' opinion. But, according to my observations comparing lower teeth of Talpa europaea and Mogera, the premolars of Mogera fully developed enough and rather it lost two teeth at the anterior portion out of premolars. Because, in the lower jaw of Talpa europaea, the four front teeth are all small, but the fourth or outer-most of them is called the lower canine, for, when the teeth are closed, it passes in the front of the upper canine. Nevertheless the tooth which does the work of a canine is the fifth. This is two rooted tooth and conforms so closely with the three teeth behind it in configuration, that it is obviously only one of these premolars developed to a larger size than the others. Indeed, this is the first premolar and closes behind the upper canine. The remaining three premolars are rather small and three molars sre considerable size. Of Mogera, however, in the front of lower jaw come three small teeth only, but the next tooth which is of considerable size, is similar to the first premolar of Talpa europaea, because it is a two rooted tooth and closes behind the upper canine. The remaining next behind this tooth are three premolars and three molars. Mogera has only three small front teeth, although Talpa europaea having four teeth; and the next tooth behind these small teeth is considerable size, which is the fourth in Mogera but the fifth in Talpa europaea. These teeth are almost equal one another in appearance, shape, size, bifurcation of root and occlusion. In common mammaria the tooth counting fourth from front is canine and also of Talpa europaea, but the fourth of Mogera is identification to the fifth tooth of Talpa europaea. Up to this date, the fourth tooth in the lower jaw of Mogera is admitted to the canine in configuration by mistake, but now rather I do say this tooth is the first premolar as the result of comparison with the teeth of Talpa europaea. Richard Owen said that in Talpa mooguru Temm.(suppose Japanese mole), the lower canine is abscent. Either the lower canine of Mogera is surely absent or on the contrary to expectation presenting canine but rather one of incisors is absent. I will try to find out the plain proof about this problem.
- 社団法人日本動物学会の論文
- 1937-02-15