50 Dr. Karl Krapelin on the Pulicidse. 



course, be a maxilla, and thus the composition of the sucking 

 tube out of the two mandibles would be finally decided. Bu 

 then we should at once be enabled, in one point, to carry ou 

 a corresponding comparison between the buccal organs of the 

 Pulicida3 and Rhynchota, inasmuch as we need only suppose 

 the labrum of the latter, which is indeed often enough developed 

 into along, slender, stylet-like organ, to sink from above be- 

 tween the mandibles*, in order to arrive at conditions which 

 might perfectly well be placed side by side with those occur- 

 ring in Pulicidse (compare fig. 11 with fig. 15). It appears 

 further that upon the basis of my conception a connexion 

 might be established between the modes of discharge of the 

 saliva in the Pulicidge and Rhynchota, if we assume that the 

 paired half-grooves along the inner side of the mandibles of 

 the Pulicidge (fig. 13, s) have coalesced in consequence of the 

 changed adhesion of these jaws, caused by the emergence 

 of the labrum, as a constituent of the sucking-tube, into an 

 unpaired efferent canal (figs. 11 and 14, s). The variable 

 part taken by the two mandibles in Hemiptera and Cicadge 

 (see fig. 14) in the formation of this salivary tube would 

 come in support of this hypothesis. Among the lihyn- 

 chota, as is well known, a hypopharynx is not developed as a 

 separate organ, or only as a rudiment (in Cicadaj), so that in 

 this circumstance also a parallelism between Pulicidge and 

 Bugs may be found. 



The labium of the Rhynchota consists of four consecutive 

 cylindrical joints furnished with a deep longitudinal groove 

 along the upper surface. It has been said that it is destitute of 

 pgilpi, but I think that this mode of expression is not correct. A 

 labium divided into four or five successive rings is in complete 

 contradiction to the plan of the organ deduced from the con- 

 sideration of the masticating mouth. But notwithstanding 

 Geise's assertion to the contrary {I. c. p. 11), there is nothing 

 to prevent our regarding the cylindrical and often much more 

 voluminous basal part of the labium as the submentura 

 and raentum, as a direct continuation of which arise the 

 multiarticulate palpi fused together in the median line. 

 That there is really an amalgamation in the terminal 

 joint of the labium is rendered probable by the circum- 

 stance that both in the Hemiptera and in Cicadge a pretty 



* Geise asserts sometliing of the kind when he represents the labrum 

 in C'oriva and Sigara as taking part with the constituents of the sucking- 

 tuhe {I. c. p. 53, fig. 29) ; unf(jrtunately I must reject this assertion — 

 welcome as it would be to me tor the homology attempted above — as 

 positively erroneous. 



