8 THE entomologist's RECORD. 



article or to make anything of the plates which accompany it. They 

 confessed that they were completely mystified and had given up the 

 attempt in despair. These facts have induced me to make the follow- 

 ing critical suggestions, in the hope that they may assist future writers 

 on this most important branch of entomological study in making their 

 communications such as can be more easily undei'stood by the student. 



With the avowed and modest object of Mr. Bethune-Baker's paper 

 I have, of course, no quarrel. Although perhaps it is a little belated 

 to set out to prove the Jong established fact that genitalic differences in 

 lepidoptera have both specific and generic value. One of my corres- 

 pondents wrote that it was hardly worth while going through so much 

 to get so little. 



The points I wish to deal with concern rather those matters which 

 make the paper so difficult, or even well nigh impossible, to follow, 

 and are these : (i) The use of photographs for the plates ; (ii) the pro- 

 file method of mounting the genitalia; and (iii) the employment of 

 unrecognised names and descriptive phrases for the various parts and 

 organs. 



(i) First, I am convinced that photography is far from being a 

 happy method of depicting the structure of the genital organs. It is 

 one thing to see the mount through the microscope and quite another 

 to see the reproduction in the photograph. A photograph, while from 

 one point of view showing too much, i.e., parts that have no particular 

 significance, from another point of view conceals far more than it 

 reveals. Even in the best photographs the superimposed masses give 

 such a confused picture that the organs cannot be discerned, whilst 

 many important features do not appear at all. The result is that only 

 a very small percentage of the parts described in the text can be made 

 out with any degree of certainty in the plate, and when, as in the 

 article before me, an unscientific printer, whose only idea is apparently 

 to fill up a blank space, has used every possible variation in the position 

 of the figures, and when, moreover, the figures appear without titles, 

 the student has to add sleight of hand to his other qualifications, for he 

 must keep the book open at three places, whilst he twists in all direc- 

 tions in order to get the figure the right way up. From the point of 

 view of instructive value there is no comparison between a photograph 

 and a drawing. The latter reveals to the student what the master's 

 eye can see, and whilst obscuring and unimportant parts can be omitted 

 it is possible to present with clearness every feature and organ that is 

 of characteristic and distinctive value. With a drawing it is possible 

 to follow the descriptions of the text, with a photograph this can only 

 be done in part, and that with the greatest difficulty. 



(ii) In the second place I would suggest that while the method of 

 mounting the genitalia so as to give a side view is occasionally neces- 

 sary, in most cases the ventral view discloses the organs in a far more 

 comprehensible manner. It is only necessary to lay the abdomen on 

 its back and then turn back the enclosing valvae to allow the student to 

 see right into the genital cavity, with all the organs visible and the 

 paired organs systematically arranged. A glance at the object thus 

 mounted will reveal what it w^ould take a very long study of the side- 

 way mount to discover, and much more that the latter method could 

 never show. 



(iii) In the third place, I do most earnestly deprecate the employ- 



