Dr. Karl Krapelin on the Pulicidae. 49 



ledge it cannot well be maintained that there is a clear imi- 

 tariness of structure in the buccal organs of the Rhynchota, 

 as, at any rate among the Aptera (the Pediculina and Mallo- 

 phaga), conditions occur which depart widely from those of tlie 

 more highly organized groups. But as the arguments upon 

 this point are not yet closed and I have made no investigations 

 upon these lower forms, we must content ourselves with 

 examining at least the sucking-apparatus of the Hemiptera 

 and Cicadae in search of any agreement with the proboscis 

 of the Fleas that may exist. With regard to the arrangement 

 of the parts of the mouth in these higher groups of the Rhyn- 

 chota, I have already published some statements in a previous 

 note *, and these observations have since been confirmed and 

 extended by Geise f- According to these the true sucking- 

 tube of the proboscis is formed by the two maxillee closing 

 laterally against each other into a double tube, while the 

 mandibles are placed alongside of this tube as lateral piercing- 

 setfe. From more recent investigations I do not hesitate to 

 declare this view J so far erroneous that it is not the maxillne 

 but rather the mandibles that interlock in the median line to 

 form the sucking-tube (see figs. 11, 14). I am led to this 

 changed interpretation of the two pairs of jaws in the first 

 place by the fact that in transverse sections through the head 

 the lateral setse finally come to be the lower ones, as, indeed, 

 Geise correctly shows in his figs. 25 and 31. Secondly, I 

 think that in the Cicadae I have found distinct traces of basal 

 joints of the maxillae connected with the outer setffi. Fig. 12 

 shows the lower part of the face of a large tropical Cicada. 

 On each side of the broad labrum (Ir) there is here an oblong 

 plate ipl), which terminates almost in the middle line 

 beneath the labrum in a blunt hairy tubercle and a peculiar 

 whip-like appendage (fig. 6,/) . If this structure be prepared 

 out of the head, a connexion, certainly only by articulation, 

 with the lateral piercing sette may be easily demonstrated, 

 for protrusion and retraction of which not only the chitinous 

 sinews (fig. 6, sp and sr), but also the corresponding muscles 

 (tig. 6, pm and rm) are attached to this chitinous piece. If 

 this interpretation of the chitinous piece occurring in all 

 Cicada3, I ulgorinse, &c., as the basal part of a jaw, perhaps 

 even with palpiform appendages, be correct, this must, of 



* Zool. Anzeiger, 1882, p. 574. 



t G-eise, ' Die Mundtheile der Illiynchoten ' (Bonu, 1883). 



X On my part this resulted merely from what I now believe to be a 

 wholly unjustified homologiziiig with the buccal organs of the Lepido- 

 ptera, the sucking-tube of which is undoubtedly formed of the maxilla 

 (see also Kirbach, Zool. Anz. 1883, p. 553). 



Ann. iic Mag. N. Hist. Ser. 5. Vol. xiv. 4 



