IXTBODUCTIOI^. 17 



are uinisually elongated, and in various genera of Crypto- 

 RRHYxciiiN.Ti; the front tibise or tarsi may be fringed with long 

 hairs in this sex ; in certain OTiORRKYSCiiiNJE—S'i/stutes (Africa)^ 

 Cyrtozemia (India) — the bind or middle tibias are often stronglv 

 curved or tootiied in the males. 



One of the few cases in which the two sexes have been re- 

 garded as distinct species is the African Polycleis lonc/icornis, 

 Fhs. ; not only is the colouring strikingly diflerent, "but the 

 shape of the prothorax is quite dissimilar, and the antennae are 

 much longer in the male. Another remarkable sexual character 

 is the long spine which projects forwards on each side of the 

 prosternum in some Qentrinus (America) and Mecojms ; and the 

 hairiness of the males in Hypomeces (India) is an uinisual form 

 of dimorphism. Tlie reason for the extraordinarily elongate 

 liead in the males of some Apodenis is by no means' clear,' but 

 the two hooks at the apex of the tibia in the female (the male 

 having only one) is doubtless connected with her leaf-rolling liabits. 



StriduJation. 



The stridulatory apparatus in Curculioxid^ has received but 

 little attention, and in 1900 Dr. C. J. Gahan briefly summarised 

 what was known on the subject (Trans. Enfc. Soc. Lond. 1900, 

 pp. 449-451). So far as has been ascertained at present, these 

 organs are confined to the Hylobiin^, Cry^ptorrhyxchin^, 

 CEUTHORRHTNCHiNiE, and souie allied groups. In all the cases' 

 known to Dr. Gahan the soui^d is produced by the rubbing of 

 the pygidium or propygidium against the apex of the elytra, and 

 this may be effected in two ways:— (1) the files may be situated 

 on the under surface of the elvtra, along the apical portion of 

 the suture, the scrapers consisting of a number of granules on 

 the pygidiinn ; or (2) the files may be placed on the pj'gidiuni^ 

 while an oblique ridge near the apex of ench elytron serves as a 

 scraper, against which the file is rubbed by a u'lovement of the 

 abdomen. In some species, such as the European Cryptorrluin- 

 chus IcqMtthi, L., tlie stridulating mechanism is found in the 

 male sex only, the files being placed on the elytra ; in others, 

 belonging to the genera PlintJms, Accdles, Mononychus, etc., the 

 organs occur in both sexes, the files being again on the elvtra; 

 while in a third group, first recognised by Dr. Gahan, both sexes 

 are able to stridulate, but the files are on the elytra in the males 

 and on the pygidium in the females. To the last-named group 

 belong certain species of the following Indian genera : Crypto- 

 rrhynchus, Campton^hinus, Gasterocercus and Ectatorrliinus. 



Larva'. 



Despite their undoubted economic importance, extremely little 

 is known about the early stages of Indian Curcclionid.e, and, 

 indeed, this applies to the family as a whole; for even in 



c 



