258 KANSAS UNIVERSITY SCIENCE BULLETIN. 



cbitinous structure, which Geise does not find in his specimens. 

 The injector is very much the same as described by Geise. 



Leon uses Pentatoma as the subject of his investigations, and, 

 in a great measure, reproduces the work of Geise. The most 

 interesting part of his paper is his discussion of the morphology. 

 He considers the maxillary palpus as having disappeared with 

 the maxilla's change of function. On one of the Tingitida3 

 from Ceylon he finds vestigial three-segmented labial palpi. 

 He presents this fact as an argument for the belief that the 

 labial palpi are lost in the Hemiptera, and that the labium is, 

 therefore, composed of the submentum, mentum and glossae 

 and paraglossae fused to form the terminal segments. 



The Cicada nymph was used by Smith in his investiga- 

 tions. His explanation of the mouth-parts is, in brief, the 

 following : The anterior sclerite on the cephalic aspect of the 

 head is the labrum. Just behind the labrum is the man- 

 dibular sclerite, which is the true mandible. The maxilla is 

 represented by the two stylets arising from one base, to which 

 is attached the vestigial maxillary palpus, and by the sheath, 

 usually recognized as the labium. The bristles represent the 

 lacinia and the stipes of the maxilla, according to his work. 

 The development has been the same as in the case of the Dip- 

 tera. The basal joint of the beak is the cardo, the second 

 segment the subgalea, and the third and fourth the two joints 

 of the galea. All that remains of the labium is the mentum, 

 a boat-shaped process lying between the stylets. 



Smith's homologies seem to be fanciful. He apparently felt 

 determined to make the changes in the mouth-parts correspond 

 to those already found in the Diptera. In his dissections he 

 seems to have overlooked the fact that the stylets do not arise 

 from one base. Had he observed this, it would have been evi- 

 dent to him that his theory would not hold good. The boat- 

 shaped process which he names the mentum will be recognized 

 -as the pharynx. Smith's paper has been severely criticized by 

 Marlatt. Marlatt gives Smith well-deserved credit for calling- 

 attention to the mandibular and maxillary sclerites, but at the 

 f-;ime time he refuses to accept the explanation of the morpholo- 

 gies. 



The morphological development of the Hemiptera has been 

 investigated by Heymons (1899) . It is gratifying to know that 



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