OF WASHINGTON, VOLUME XIII, 1911. 129 



(Choriou-Anhaenge). The well known biologist Heymons 1 

 expresses the same view in one of his papers. Some scientists 

 still adhere to the older theory. It seems, therefore, that 

 further research in this interesting matter may be necessary 

 in order to state positively the real function of these peculiarly 

 formed organs on the eggs of Hemiptera. 



The egg-shell or chorion is formed, according to Dr. 

 Korschelt, 2 by cuticular secretion of the epithelial cells in the 

 oviduct. It consists usually of two layers, which differ in 

 thickness and texture. The smaller eggs have the texture 

 of the outer surface of the chorion more or less smooth or 

 minutely granulated, while in the larger eggs it is very uneven, 

 covered with polygonal cells, often spinous and tubercular, 

 probably to give more consistency to the egg-shell. In the 

 mature stage of the egg the head of the embryo is always di- 

 rected towards the apical part or upper egg-pole, where in 

 some groups of eggs a round or oval shaped lid or cap is no- 

 ticeable; in other groups, mostly in those of a cylindrical 

 form, this is absent. Globular eggs are affixed to their 

 support often by a circular or bell-shaped plate; the round and 

 oval forms in some of the groups are laid loose on the ground 

 or in water, and the cylindrical eggs are usually deposited in 

 the tissue of plants and in cracks. 



According to Leuckart the shape of the processes before men- 

 tioned is characteristic for the eggs of certain groups and in 

 doubtful cases may be of great value for the systematist. 



Prof. O. M. Reuter 3 in a recent publication expressed re- 

 peatedly his opinion of the necessity also of studying the eggs 

 as an aid to classification. 



In recent years American writers, in working up the life his- 

 tory of hemipterous species, have greatly contributed to our 

 knowledge of the eggs by publishing detailed accounts. There 

 are, undoubtedly, several distinct types amongst these eggs 

 whereby can be demonstrated the relationship of the species and 

 genera to the families. For instance, all eggs of species belonging 

 to the family Pentatomidse are uniform, only slightly modified, 

 generally barrel-shaped, or resembling very much the form of a 

 tiny tin-can, as in Pentatoma IiataS Murgantia histrionica* 

 and Stiretrus anchorago. All these eggs have a round apical 



1 Zeitschrift fur wissenschaftliche Insectenbiologie, Band ii, 1906. 

 2 Zur Bildungder Eihiillen der Micropylen und Chorionanhange bei 

 den Insecten. Nova Acta d. K. Leop. Carol. Acad., Bd. ii, 1887. 



3 O. M. Reuter, Phylogenie und Systematik der Miriden. Acta 

 Societatis Scientiarum fennicae. Tom. xxxvil, No. 3, 1910. 



4 A. W. Morrill, U. S. Dept. of Agr., Bureau of Entomology, Bui. 

 64, Part I, pp. 4-8, 1907. 



5 C. V. Riley, 4 Ann. Report Ins. of Missouri, 1872, p. 37. 



