INTItODUOTIOJ^^. XI a 



ridge is rarely wanting; and is represented among normal Coleoptera, so 

 far as I have examined, only in certain Buprestkke. 



These characters taken collectively, in addition to the two fundamental 

 defining characters first mentioned, indicate a profound diflerence in or- 

 ganization, which isolates the Ilhynchophora from all other Coleoptera. 

 From this isolation results the necessity of classifying them upon other 

 characters than those which are found useful in defining series and fami- 

 lies in the normal Coleoptera. The great resemblance in general appear- 

 ance of the insects of this type, and the endeavor to consider them as only 

 a family in the whole series of Coleoptera, has caused the characters used in 

 tills memoir to be either undervalued or overlooked. I believe, however, 

 that when attention is directed to them, and to certain other characters, 

 which I have not had time to fully investigate, the arrangement of these in- 

 sects into natural groups will be found as simple and intelligible as that of 

 the normal Coleoptera. 



Among the investigations which j^et remain imperfect, I would mention 

 as specially deserving of attention, the stridulating organs. There are in 

 some genera spaces on the inner surface of the elytra, which have a pearly 

 lustre, and which are probably capable, by friction against the ascend- 

 ing margin of the ventral segments, of producing a sound. I have men- 

 tioned these under the genus Listronotus, of the Phytonomini, but they are 

 present in many genera of other tribes, and in fact, the Gonotracheli and 

 many others are known to emit a squeaking sound. 



The homologies of the parts of the head, by reason of which the front por- 

 tion becomes extended into a beak, and the basal piece on the under surface 

 (which separates the gular sutures in normal Coleoptera) disappears, are also 

 worthy of attention; so too are the larvie, with the view of discovering 

 some general characters in which they difler from those of other Coleoptera. 



A more careful study should also be made of the antennae of the Scoly- 

 iidcB, by specimens mounted in Canada balsam, so that the homologies of 

 the joints of the funicle, when they disappear may be ascertained. The 

 subject, as treated in this memoir, is, I may say, barely sketched, and will 

 yield to others, who may devote labor to it, not only the correction of errors 

 I have made, but many new truths and generalizations greater in value 

 than those to which I have attained. 



The affinities of the families of Ilh3'ncliophora among themselves, and 

 their resemblances to various series or families of the normal Coleoptera 

 remain to be indicated. 



The typical Rhyuchophora, Curcullonidm, while exhibiting in the dif- 

 ferent tribes characters which are more individualized and combined with 

 special structures in the other families, occupy a central position around 

 which the latter may be grouped. 



The Rhinoviacerida', by the presence of a labrum and flexible palpi, as 

 well as by the general form of b()dy,and 11-joiuted, nou geniculate antennre, 

 indicate a resemblance to Rhiuosiiuus, &c., of the PytliidcB. The Otio- 

 rhy7ic7iidm, in the tribes with large mentum, and the Br achy cer Ida show 



