107 



apex, bounded behind by a small tooth or swelling (figs. 

 102-104, 108), and not running on to the general line of the 

 tibia, notches of this character have been, and are here, 

 regarded as of generic importance. Frequently, however, the 

 tibiae near the apex are fclothed (at the position of the notches) 

 with some silvery hairs, and in certain lights these cause the 

 tibiae to appear notched ; where the apex of the tibia is dilated 

 and the incurved space behind same runs on to the general line 

 {figs. 133 and 135) this has not been considered as a true notch. 

 A notch is frequently at the apex itself, and in such the basal 

 joint (or part of same) of the tarsus can rest ; it is usually due 

 to a strong ridge or carina on each side of the upper edge of 

 the tibia, which at the apex project on each side of the notch 

 like flanges. On some species (figs. 128 and 141) also there is 

 a more or less triangular notch at the lower apex (or near 

 same) of the front, or of the four hind ones, or of the hind 

 ones only. The notches in the upper-surface or apex are not 

 •confined to one sex, although they are sometimes more pro- 

 nounced on the males than on the females; but when on the 

 lower-surface of the hind tibiae they are confined to the males. 



The pygidium frequently semi-circularly encroaches on 

 the apical segment of the abdomen, so that this appears to be 

 composed of six segments instead of five ; this is usually more 

 noticeable on the males than on the females. Although the 

 greater portion of the pygidium is normally concealed, it is 

 sometimes accidentally uncovered, and on all such specimens 

 its hind part is seen to have a deep median groove. 



In a subfamily many of whose species are characterized 

 by great variability of size and colour, it is desirable that 

 structural features, not (or but little) liable to variation, should 

 be fully noted ; and it is curious that, almost with the sole 

 exception of the late Rev. T. Blackburn, the strongly-marked 

 sexual features of the abdomen and legs should have been 

 overlooked, and yet these lead to the rapid and certain 

 identification of many species. Unfortunately, with many 

 species such features cannot be noted with specimens set . out 

 on cards in the ordinary way, it being necessary to mount them 

 so that both surfaces may be readily examined. In the tables 

 given use has frequently been made of masculine characters ; 

 no doubt tables that could be used for both sexes would be 

 more convenient, but so many species are closely allied, and 

 the characters that would have to be used for both sexes are 

 so unsatisfactory, and dependant upon comparative degrees, 

 that it was considered much better to use the frequently highly- 

 characteristic male features. In probably no other subfamily 

 of the Chrysomelidae Sire these so useful in distinguishing the 

 species, although in Rhyparida and a few other genera they 



