1908.] 



2G3 



them ; but, except in a few cases, their differences in this respect are 

 too slight, and apparently also too capable of varying in individuals, 

 to be of much practical value. 



To realize the characters of the antenna? they should be looked 

 at sideways, not from above. In this aspect it will be found that 

 those of certain species are long and slender with nearly parallel- 

 sided joints throughout and every joint many times more long than 

 broad, while others are comparatively short and stout with at least 

 the sub-apical joints compressed and dilated. In the clypeus we have 

 to notice whether the emar^ination at its apex is deep or shallow, and 

 to what extent it is interrupted in its middle by a sort of tooth-like 

 projection, which is really the apex of a more or less distinct carina 

 following the longitudinal diameter of the clypeus. The characters 

 of the claws are difficult to see. They are bifid in some species, and 

 nearly or quite simple in others, the former being the most usual 

 condition ; but a claw which is really bifid only looks so in pnrtieular 

 aspects, and it is not always possible to get a clear view of it in those 

 aspects, the hairs, or the pulvillus, or some other obstacle getting in 

 our way. 



The following outline sketches* (figs. 12 and 13) will, T hope, 

 assist collectors in making use of my table of characters for this 

 genus :- 



Figure 12. 

 Apical outline of clypeus in certain 

 Paecilosoma spp. 



Fig. 13. 



Antenna characters in certain 



Pcecilosoma spp. 



a. excisa, Thorns. 9 d. liturata, Gmel. 9 a. l-lugi, Steph. § d. immtrsq, Klug. ? 



6. klugi, Steph. $ e. longicornis. Thorns. 9 b. liturata, Gmel. 9 e. longicornis, Thorns. 9 

 c. immersa, King. 9 /. tridens, Knw. 9 c. excisa, Thorns. 9 /. tridtns, Knw. 9 



* Those in fig. 12 were traced from photo-micrographs of specimens from which the 

 mandibles and labrum had been removed to show tbe outline of the clypeus more clearly. 

 Those in fig. 13 were obtained rather differently. The objects were set up as though to be 

 photographed, and the images thrown by them on the focussing screen were traced through 

 paper laid upon it. Until I thought of this simple device, I .always employed a " camera 

 lueida " to obtain my records of structural details in the insects I was studying. But I find the 

 focussing-screen method so much less troublesome, that I expect in future to make much 

 use of it. 



