400 



DR. F. LEUTHNEE ON THE ODONTOLABINI. 



The gap between the mesodont and telodont forms long remained unbridged. It is 

 true that, on a careful examination, I met with mesodont forms in which the mandibles 

 were as long as in dux\ and in many specimens they were smooth, convex, and curved, 

 resembling the amphiodont forms of 0. siva, as in Petiver's specimen in the British 

 Museum ; but the central tooth was always strongly developed. Nevertheless I 

 expected, if I could obtain more extensive materials, to discover mesodont forms with 

 mandibles of similar form, but with only the rudiment of a central tooth. If two 

 teeth had disappeared, why should not the third disappear too "? At length I chanced 

 to meet with what I had sought for so long in the Museum of the Jardin des Plantes 

 (no. 8). This discovery resolved my last doubts, and completed the series to the highest 

 form. 



Diagram exhibiting the different Stages of Development of the Mandibles in 



Odontolahis alces, Fabr. 



dux . . 



alces . . • f. mesodoiita. 



f. telodonta. 



f. amphiodonta. 

 f. priodonta. 



The preceding remarks are sufficient to show with what ease we can pass from the 

 priodont to the telodont form in this species ; but if we commence with the telodont 

 form (as Prof. Westwood has done) we shall find it difficult to explain the origin of the 

 mesodont form. The modifications of the mandibles affect not only their form, but 

 their functions also. The mandibles of the telodont form consist of a curving pair of 

 pincers, which can only meet at the tip. In the mesodont form the great development 

 of the middle tooth renders the use of the mandibles as a weapon (for such must they 

 be regarded, according to all indications) more probable, for the teeth are adapted for 



