500 COLEOPTERA OF NORTH AMERICA. 



witli two small fixed spurs. In Cylas the tibiie are all 

 slender, straight, and not mncronate at tip. Tarsi spongy 

 pubescent beneath, with the third joint bilobed. Claws 

 large, simple, and divergent, except in Cjdas, where they 

 are small and connate at base. 



This highly specialized family is the last of those in which the 

 male is provided with an additional dorsal segment. The mouth 

 organs vary to a greater degree than they do in Curculionida?, 

 though usually the mentum is developed to such an extent as to 

 conceal the ligula and labial palpi. Of the genera known to us 

 Cylas is the only one in which the maxilla? are exposed by the 

 mentum not filling completely the buccal cavity, though other 

 cases are mentioned by Lacordaire. 



But what is most curious, is that while the mandibles of the 

 9 preserve the pincer-form seen in many Curculionidie, and the 

 beok is slender, and in some species extremely long, for the pur- 

 pose of performing its function as an accessory organ of genera- 

 tion,* in the % the mandibles assume a flat, curved, and pointed 

 form, resembling those of ordinary Coleoptera. This sexual 

 character is exhibited even in those genera in which the beak of 

 the % is nearly as slender, and the mouth as small as in the 9. 



The explanation of this difference in the mandibular structure 

 is afforded by the interesting remarks of Mr. A. 11. Wallace, con- 

 cerning the wonderful pugnacity of the Z % when in proximity to 

 the ?. An excellent account of the assistance given by the % to 

 the 9 when she is occupied in boring the hole in which the egg is 

 l)laced, is also given by C. Y. Riley, f from observations made by 

 his correspondent W. R. Howard, of Forsyth, Missouri. 



These combats, however, result in no injury to either of the 

 parties engaged; the dense chitinous covering affords a perfect 

 protection; the weaker male, overcome by exhaustion, eventually 

 flees, and leaves to his more vigorous victor the honorable task 



* Harris, Ins. Inj. Veg. 3d ed. 68; Wallace, Malay Archipelago (ed. 

 Harper), p. 482; Riley, Sixth Annual Report, Ins. of Missoiiri, p. 115. 

 These authors mention that the 9 makes with her beak deep perforations 

 in the tree, and deposits an egg in each one of them; Lee, Amer. Journ. 

 Sci. and Arts, 18G7. 



f Sixth Annual Report on the Noxious, etc.. Insects of Missouri, 1874, 

 p. 415. 



