NO. 2242. MORPHOLOGY OF THE STREP8IPTERA— PIERCE. 413 



In TrioBocera (Mengeidae) the scutum is narrowly connected 

 with the praescutnm on each side of the anterior apex of scutellum. 

 It is greatly produced posteriorly (pi. 64, fig. 10; pi. 65, fig. 1). In 

 Mengea it is very narrowly united in front of the broader scutellum 

 (pi. 64, fig. 1). The lobes are posterior. The same condition exists 

 in Tetrozocera (Mengenillidae) (pi. 66, fig. 1). 



On the other hand, the pushing of the praescutum into the scutum 

 in the Xenoidea and subsequent families has made the scutum humer- 

 ally lobate. The bridge between the lobes occurs also in Caenocholax 

 (Myrmecolacidae) (pi. 69, fig. 1), Neostylops (Stylopidae) (pi. 70, 

 fig. 1), Cyrtocaraxenos (Halictophagidae) (pi. 78, fig. 1), and Deine- 

 lenchus (Elenchidae). 



In all other genera studied the scutum occurs as two lateral hu- 

 meral lobes separated by praescutum and scutellum (see pis. 66, 72, 

 75,76,77). 



Parascutellum. — The scutum in the more generalized genera was 

 bounded by praescutum, scutellum, and epimeron, but early in the 

 modification of the group a suture appears, beginning at the anterior 

 base of the wing and extending diagonall}'^ toward some part of the 

 scutellum. This does not occur at all in Tetrozocera (Mengenillidae) 

 (pi. 66, fig. 7), and is incomplete in Triozocera (Mengeidae) (pi. 

 65, fig. 8), Neostylops (Stylopidae) (pi. 70, fig. 4), Myrmecolax 

 (Myrmecolacidae), Ilalictoxenos^ and Crawfordia (Xenidae), Dio- 

 zocera (Diozoceridae), and Deinelenchus (Elenchidae). It is com- 

 plete in Caenocholax (Myrmecolacidae) (pi. 69, fig. 2), Xenos (pi. 

 72, fig. 1) Pseudoxenos^ and Tachytixenos (Xenidae), all Halicto- 

 phagidae (pi. 75, fig. 2; pi. 76, fig. 5; pi. 78, fig. 3), and Liburnelen- 

 chus (Elenchidae). The part behind the suture is called parascutel- 

 lum because it is beside the scutellum. 



Scutellum. — The third median sclerite of the metanotum is the 

 scutellum, which is invariably broadest at its base, and anteriorly is 

 more or less rounded or constricted. In the Megeoidea it reaches 

 forward almost as far as the scutum and is subtriangular, but 

 rounded at apex in Triozocera and more broadly rounded in Mengen. 

 In these two genera it does not separate the scutal lobes completely. 



In Austrostylops (Mengenillidae) the scutellum is very long and 

 broadly separates the scuti in front. In Tetrozocera it is similar 

 to that of Mengea. In Mengenilla it is shaped as in Triozocera and 

 narrowly separates the scuti (pi. 66, fig. 6). 



In Myrmecolax and Caenocholax (pi. 69, fig. 1) (Myrmecola- 

 cidae) the scutellum is short and broadly rounded. In Neostylops 

 it is longer and broadly rounded (pi. 70, fig. 1). 



Throughout the Xenidae scutellum is longer than praescutum 

 (pi. 72, fig. 2). In Craiofordia it is anteriorly very broad, a little 



