42 Dr. Sharp on the IlJn/ncJiopJiomus 



Ehynchophora ; here the prosternum is interrupted 

 behind by the cotyloid depressions, behind which may be 

 seen the centro-sternal piece, of variable size according 

 to the genus examined, and behind this again the con- 

 joined epimera. In Attelahidce the centro-sternal piece 

 is absent, and it is clear from what we may see in the 

 next family — Rhyncldtidm — that it is by this piece that 

 the apices of the epimera are widely separated, the 

 sutures, however, being greatly obliterated. In Rhynchi- 

 tidce the structure differs by the centro-sternal piece 

 being nearly always very small, and placed just behind 

 the coxae, penetrating to a greater or less extent between 

 the apices of the epimera, and in some genera entirely 

 separating them. Thus this family shows that, so far 

 as the prosternal structure is concerned, no sharply- 

 marked distinction exists between Coleoptera with the 

 apices of the prosternal epimera conjoined and Coleoptera 

 with them separated. This exceptional character* in the 

 Attelahidce and Rhynchitidce, combined with the straight 

 antennae, and the absence of mechanical apparatus in 

 the gizzard (ef. Lindeman, Bull. Mosc. li., 1876, p. 161, 

 &c.), indicate that these two families are correctly placed 

 at the commencement of the Rhynchophora. 



The habits of the species of RkyncJtitidce are very 

 varied, and some of them exhibit very remarkable 

 instincts ; and it is therefore interesting to find that the 

 details of their external structure are as varied as their 

 instincts. The fact that there exists so much discrepancy 

 in their structural details, however interesting it may be 

 from a biological point of view, certainly renders the 

 establishment of natural genera a very difficult matter. 

 The form of the rostrum, the structure of the ventral 

 segments and pygidium, and the structure of the hind 

 parts of the prosternum, all vary somewhat from species 

 to sj)ecies ; so that if the genera be founded on any one 

 of them exclusively, the line of division chosen will 

 necessarily be a more or less arbitrary one : by giving 

 attention to more than one character, the genera may, 

 I think, be perhaps made more natural, as it frequently 

 happens that in a species where one character diagnostic 

 of the genus is feeble, a second exists in undiminished 



* I do not mean by this that these are the only Ehynchophora 

 in which this character exists ; and indeed there are others in 

 which the apices of the epimera are not conjoined. 



