Dr. Karl Krapelin on the Pulicidae. 39 



Coccidffi. Nay, even if we add the footless larvee and the 

 fusion of the thoracic segments as further criteria, we might 

 perfectly well unite the Bees with the Diptera. It is not the 

 simple fact of the suctorial buccal organs that is of importance, 

 hut their specific structure, the position and arrangement of 

 the parts composing the suctorial apparatus. If we fix our 

 attention upon this point we at once recognize that the fly's 

 proboscis is constructed upon a perfectly different fundamental 

 plan from that of the Apidee, that the two are not directly 

 phylogenetically referable to each other, but that, on the 

 other hand, the great variations in the buccal apparatus of the 

 Diptera only represent modifications of one and the same 

 type, distinctly demonstrable throughout. The characteristic 

 of the bee's trunk consists in the development of the loivar 

 parts of the mouth into the sucking organ, while the man- 

 dibles retain their original function ; that of the fly's pro- 

 boscis, on the contrary, in the employment of the labrum and 

 hypopharynx for the formation of the sucking-tube, with 

 which the mandibles and maxillae associate themselves as 

 St} lets more or less developed as required, while at the same 

 time the labium in all cases has to form a protective sheath 

 for the comparatively delicate tube through which the fluids 

 ascend. Tliis fundamental plan of the employment of the 

 parts of the mouth occurs, as already pointed out in the 

 introduction, in all the groups (except the Pulicidte) which 

 have hitherto been placed in the group Diptera, in the piercing 

 Culicidffi, Tabanidse, and Asilidas, the difterent families of 

 honey-suckers, and the Pupipara, which are so depressed in 

 position through parasitism ; nay, a bridge seems even to be 

 thrown over towards the rudimentary buccal organs of the 

 CEstridee, through the structures which occur in Gutereh^a. In 

 figs. 1-3 (PI. III.) I have drawn transverse sections of the pro- 

 boscides of those groups of flies which, upon one hand or the 

 other, have been referred to as allied to the flea. While those 

 of Tabanus and Gulex (figs. 1 and 3) agree not only in the 

 position but also in the number of the pieces composing the 

 proboscis, that of Melojyhagus (fig. 2, the representative of the 

 Pupipara) shows a great reduction, which finds its expression 

 in the entire absence of the mandibles and maxillas* ; but 

 * The two valves embracing tlie proboscis of the Pupipara have 

 been very erroneously interpreted as maxilla3, their palpi, or even 

 as a bipartite epi pharynx (Meinert). From the whole arrangement of 

 the proboscis, wliich is freely movable in a wide cavity of the head 

 extending as far as the prothoracic ring, we can here have to do only 

 with a conical prolongation of the head which has become paired, some- 

 what such as we should obtain if we imagined the slight emargination 

 at the apex of the frontal cone of Hhingia carried down to its base. The 

 strongly projecting cheeks of many Conopidte might also perhaps bo 

 regarded as analogous, 



