360 ME, a. LEWIS ON JAPANESE LANGHTBIID^. 



In all tlie species of the ingens section there is another notable 

 sexual character — the thorax in the male is of much greater con- 

 vexity than in the female. This development appears to be such 

 as Dr. Leuthner has noticed in certain Lucanida?, for the pur- 

 pose of providing the necessary space for storing the muscles, 

 which have enlarged gradually from the energy of the fore legs 

 during the exercise of the functions I have referred to. In 

 Doubledaya the thorax has a longitudinal furrow down its centre; 

 and it is therefore probable that the muscles of the legs only 

 occupy the spaces on each side of this groove ; or, if the muscles 

 meet in the centre, and form a compact mass, the chitinous 

 covering is drawn down upon them. 



In conclusion, let me add a word on the tarsal development of 

 Doubledaya, as it appears to be different in some respects to the 

 ordinary sexual dilatation in the Coleoptera. It is in fact only 

 partially sexual. It is in part such as we find in Garabus S , and 

 part such as we see in both sexes in Chrysomela ; in the first 

 as being in a degree sexual, in the second as being suited for 

 clinging to foliage. Some of us have seen Timarcha on foot- 

 paths and herbage in spring and early summer, and noticed the 

 slow drawly movements of the legs. The tibisB are lifted well 

 oW the ground and passed forward in a perpendicular position, 

 then let down, and after that there is another movement. This 

 is a movement of the tarsus by which it becomes firmly attached 

 to the leaf; and this is independent of, and subsequent to, 

 the movement of the legs. This is the action or tise which, 

 to my mind, gives the breadth to the tarsi of Chrysomelidse, 

 causing three joints to dilate and absorb tissue at the expense 

 of two others which become obsolete. In DoiMedaya there is the 

 Ohrysomela-foTVQ. of tarsus, existing in both sexes, and an extra 

 breadth in the male, as in Garabus. The extra breadth enables 

 the male to cling to the foliage when seated over the female, as 

 specimens placed in this position show ; and here also the utility 

 of the shorter legs in the male becomes evident. In Garabus 

 there is not this double function in the dilated tarsi, but there 

 is in some of the smaller genera of the Carabidse. In Gallida 

 and other foliage-species all the tarsi are fairly ample, and of 

 nearly the same breath. In Garabus and Pterostichus, where 

 great dilatation is observable, and confined to the fore tarsi, the 

 species copulate in open spaces, and the fore tarsi are then used, 

 as I believe, to arrest the progress of the female, which at this 



