2io E VOL UTION AND DISEASE. 



fessor Sir W. Turner. The illustration (fig. 112), which 

 was prepared from a model of this specimen, represents 

 the anterior part of the rostrum and lower jaw with two 

 teeth of Mesoplodon layardi. This whale has only one 

 tooth in each mandible (at least, as far as we know). In 

 the present case the fangs of these teeth had become 

 greatly elongated, and after emerging from the gum had 

 curved backwards, upwards, and inwards, so as to cross 

 each other on the dorsal surface of the whale's beak. 

 The anterior border and inner surface of each tooth was 



FIG. 112. The rostrum of Mesoplodon layardi, showing the curved 

 and elongated mandibular teeth. 



smooth where they rubbed together during the move- 

 ments of the mouth. The size of these teeth is as 

 follows : The extracted tooth measures 35 centimetres, 

 1 6 of which were embedded in the alveolus, or surrounded 

 by the gum. The breadth of the tooth where it emerged 

 from the alveolus was 9 centimetres. At the time this 

 specimen was submitted to Turner, he was fortunate 

 enough to receive a young specimen of Mesoplodon 

 which enabled him to determine the nature of the 

 various parts of this abnormal tooth, and he came to 



