MEEK : MOUTH-PARTS OF THE HEMIPTERA. 275 



tracts and found those of the males as well developed as those 

 of the females. 



In brief, then, the cicadas do not differ in their feeding habits 

 from other Homoptera. Both males and females feed. If con- 

 fined, they soon die from lack of nourishment. Occasionally 

 orchards suffer severely from loss of sap given up as food. 



MORPHOLOGY. 



The morphology of the hemipterous mouth-parts still remains 

 uncertain. Various interpretations have been presented, but 

 the only ones on which investigators agree seem to be these : 

 The parts are appendages of the head segments. The inner 

 stylets correspond to the maxillce, the outer to the mandibles. 

 The sheath is made up of the labium and labrum. 



No one attempted to work out the subject from an embryo- 

 logical point of view until Heymons. His results are valuable. 

 At an early stage the appendages of all the head segments ap- 

 pear. The size of the clypeus is especially remarkable. The 

 labrum appears late. The second maxillse, which later fuse 

 and form the labium, seem to have a tendency to fuse with the 

 thorax. This fact accounts for the characteristic position of 

 the beak in all Homoptera. The first maxillae soon divide 

 into a medial and a lateral lobe, termed the lobus internus and 

 lobus externus. The medial lobe, termed the "Lade," together 

 with the mandible, soon become retort-shaped, and later develop 

 into the maxillary and mandibular setse. The latter portion, 

 the ''Maxillenhocker," extends backwards and gives rise to the 

 maxillary sclerite. The maxillary process appears early in the 

 embryo. The top of the head is formed by large lateral lobes, 

 the "Kopflappen." The sides of the head owe their origin 

 mostly to the lateral maxillary lobe. The lorse or mandibular 

 sclerites are related to the mandibles in much the same way as 

 maxillary sclerites are to the maxillae, but their origin is not 

 made clear. 



All of this knowledge is valuable, but it is not yet complete. 

 Such questions as "What part of the typical maxillae do the 

 setae represent, what has become of the maxillary and labial 

 palpi, and what parts of the second maxillae have fused to form 

 the labium ?" are yet unanswered. Embryological work, sup- 

 plemented by the anatomical, will probably solve the problem. 



With the exception of figures 1 , 2, and 4, the drawings for this 



