XXX INTRODUCTION. 



thorax the apex is the portion next the head, the base the portion next 

 the elj'tra ; in the elytra the case is reversed, the apex being the posterior 

 portion and the base the part that meets the base of the thorax ; the 

 base of the femora is the part next tlie coxas, the apex the part adjoining 

 the tibia3 ; in the segments of the abdomen the apex is the part nearest 

 the apex of the elytra, the base the part nearest the base of the elytra ; 

 with regard to the tibi« there is considerable confusion ; some authors 

 regard the apex of the tibia as the part that meets the apex of the femur, 

 the base being the portion nearest the tarsus ; others, however, take the 

 opposite view. Dr. Sharp writes to me as follows : " There is a very 

 simple means of regulating the use of the terms base and apex, and I 

 always adhere to it myself. All the parts of the body are considered 

 with relation to one point, the centre, to which they are supposed to be 

 directly or indirectly attached ; the part nearest this point is the base, 

 the part the most distant the apex : " in the following work Dr. Sharp's 

 rule has been adhered to, except with regard to the tibiae in the case of 

 some genera the descriptions of which were printed before I hac\ 

 discussed the question with him. 



