March, '09] ENTOMOLOGICAL NEWS. 99 



phic orders such as the Neuroptera and Coleoptera. The wing- 

 bearing tergiim of an adult Orthopteran is simply that of the 

 nymph plus a sclerite developed behind the former. That is, 

 the nymphal notum, from the entire lateral margins of which 

 the wings are developed, becomes the wing-bearing plate of 

 the adult tergum, but, in all the principal winged orders ex- 

 cept the Orthoptera, a second tergal plate is developed in the 

 adult behind the wing-bearing plate. This second plate is 

 highly developed in the Lepidoptera, Hymenoptera and Dip- 

 tera, especially in the mesothorax where it bears the large 

 phragma that shuts off the cavity of the thorax from that of the 

 abdomen. Sometimes it is reduced and hidden between, or 

 even within, the segments. It is never present in the prothorax. 



The words "tergum" and "notum" are commonly used inter- 

 changeably to denote all the dorsal sclerites of any segment. 

 Audouin (1824) established this use of the word "tergum," 

 while Burnmeister (1832) and Newport (1839) used "notum" 

 in the same sense. Since, now, it is obvious that we need one 

 term to signify the entire dorsal chitinization of a segment and 

 two others to designate the individual plates, the writer pro- 

 poses to retain the name tcrgum as the general term applying to 

 all the chitinous parts of the dor sum of any segment, and to 

 limit the word notum in its application to the anterior or wing- 

 bearing plate. The two terms used in this manner are, hence, 

 still interchangeable in all cases except in the wing-bearing 

 segments of most adult insects where the tergum acquires the 

 secondary posterior sclerite. This latter may be called, on ac- 

 count of its position, the postnotum, or from the fact that it 

 is not a primitive tergal plate, the pscudonotum. 



The second term has already been given to it in the Euplex- 

 optera (Dermaptera) by Yerhoeff (1903) and adopted in a for- 

 mer paper on the insect thorax by the author (1908), though 

 Verhoeff may not have intended the general application of the 

 \\nrd in this sense. The second tergal plate or pseudonotum 

 is the one usually called "postscutellum." It is a part of the 

 postscutclluui of Audouin (1824), and is the cloison costalc 

 or costal of Chabrier (1820), the postfroenum of Kirby and 

 Spence (1826), the tergum of Straus-Durckheim (1828), the 



