1888, and in previous writings, treats of the parts in a 

 similar way. 



In 1889, Professor John B. Smith of New Jersey, 

 U.S.A., in conjunction with Professor Riley and 

 H. G. Dyar, commenced a series of monographs on the 

 Noctiiidos of North America, in which he laid great 

 stress on the value of the genitalia. These monographs 

 are illustrated by rough outline drawings of one harpe 

 and clasper only, of the various species. These figures 

 were a step in the right direction, but were not carried 

 out sufficiently, and appear to me, very much like 

 illustrating a butterfly book with drawings of fore wings 

 alone. It is evident that for scientific purposes the 

 whole apparatus must be dealt with. 



In the Transactions of the London Entomological 

 Society for 1889, pp. 209, Dr. T. A. Chapman follows 

 Professor Smith in an exhaustive article on the Erebias, 

 and has also from time to time published notes on 

 various species. None of these works seem to me to 

 utilise to the fullest extent the information which may 

 be gathered from the examination of the genitalia. The 

 complete organs must be studied, for the reason that in 

 difi^erent groups, certain particular parts form the chief 

 distinguishing feature ; often the harpes are so similar 

 that reference must be made to the uncus ; at other 

 times it is the juxta that differs ; generally the penis is 

 a safe organ for differentiation. 



Recognising the importance of this, 1 resolved to 

 figure the whole apparatus, but never having been 

 taught drawing and having no natural gift I at first 

 secured the services of Mr. Henry Butler, a rising 

 young artist, and endeavoured to help him to draw what 

 I saw. His figures are signed with his initials. I drew 

 the remaining figures myself, and have also gone over 

 his, making them uniform with my own. 



The drawings are all done to one scale. At one 

 time I hoped photography would have aided their 



