Anatomy of the Male Genital Tube in Coleoptera. 641 



tion is varied. Although this point is not of great importance for 

 our purposes, the scale is in most cases indicated by a line placed 

 near the figure. When no number accompanies the line then the 

 length of the line is 1 mm. and the magnification of the figure is 

 indicated by that of the line. When a number accompanies the 

 line, the number indicates the length of the line in millimetres or a 

 •fraction of one. 



The connecting membranes between certain parts are only par- 

 tially shown in the figures. To have invariably introduced them 

 would have involved the use of shading ; and much artistic ability 

 would even then be required to distinguish the scleritic from the 

 membranous parts. The student will recollect that these membranes 

 always exist connecting the median lobe to the tegmen, and the 

 tegmen to the body wall. Sometimes a part of one of the membranes 

 is shown, and it is then indicated as such by the torn edge. 



The position shown is very frequently not a true profile, but a 

 partial one, thus allowing more of the parts to be seen and inferred. 

 The drawings have all been made from specimens in a wet, or 

 relaxed, state ; and the student must not expect to find exactly the 

 same appearances in dried and collapsed preparations. 



The figures are as a rule uniform as regards their longitudinal 

 position, the distal end being to the right so that a side-view shows 

 the left side. In a few cases, in order to show certain structures, 

 the right (not the left) side is figured ; and in that case in order to 

 make comparison more easy the figure is orientated so as to make 

 the right side look as if it were the left one, and it is stated to be 

 "reversed." 



Broken lines indicate parts that are lying below the structures 

 represented by unbroken lines. They are introduced to show the 

 continuity of portions that are not actually seen in such a dissection 

 as that figured. Where these concealed parts are the sac and the 

 duct the broken lines are reduced to dots. 



We use both single and double letters to indicate special parts. 

 The double letters are used uniformly throughout the figures, and 

 are explained below this, and more fully on pp. 481-483. The 

 meaning of a single letter will be found by reference to that 

 descriptive portion of the memoir to which the figure pertains. 



Explanation of Double Letters. 



aed = aedeagus, 



an • = anus. 



bp = basal-piece. 



cm 1 = first connecting membrane. 



