DICHOTOMY. 105 



nished with an aftershaft exactly resembling, in its 



relation to the main hair-shaft, that figured in fig. B. 



In the case of teeth it is not unusual in man to 



FIG. 52. A, feather and aftershaft of the Himalayan 

 Monaul (Lophophor^ls impeyaniis) ; B, feather and 

 aftershaft of the Emu (Dromceus novts-hollandice). 



find a double incisor or bicuspid tooth. In such cases 

 the fangs and crowns are usually firmly united together, 

 but the line of union is indicated by a deep, well-pro- 

 nounced furrow. Such a condition. of the teeth is 



