In the previous papers concerned with the fetal dentition of the fur seal, the author described that the deciduous teeth are very small and are simple in shape and that they have completely shed during the period of the intra-uterine life (’61a, b). The mammalian deciduous tooth has not been studied yet in detail except for that of the human and some animals (Diff rich,’60), but the permanent tooth has been widely investigated by many workers (Owen, 1840-45; Terra, ’11; Mummery,’24; Colyer, '36; Wiclcloson,’39; Scheffer,’51, ’60; Chaison,’57; Fujita, '57; Scott and Symons, ’61; etc.).
We described in the previous papers concerning the fur seal dentition (’6la, b) that the deciduous teeth erupt and shed during the period of the intrauterine life. Though we did not mention clearly, we presumed at that time in regard to the fate of them that they might be either swallowed into the stomach or spat out into the amnion. Terra (’11) stated that deciduous teeth of the fur seal shed during the fetal life. According to Widdowson (’39) in the walrus the milk teeth are lost at birth. Recently, Scheffer (’50) also has suggested shedding of the fur seal deciduous teeth occurs in the fetal life. However, none of them has given proof of their statements. We have carefully examined amniotic contents of the three embryos captured in the sea off Sanriku in the middle of June, 1962 and found very small teeth, which were shown in Fig. 1, in the amnion water and also in the downy hair of the embryo. As no record concerned with this subject has been located, the brief description s of what we found will be given below.