NO. 2242. MORPHOLOGY OF THE 8TREP8IPTERA— PIERCE. 425 



coxae terminate the sternum, being contiguous medially, and bear 

 the trochanters, which are much shorter than those of the other two 

 pair of legs. 



Table of species of Triozocera. 



1. Prothorax arched forward ; first abdominal spiracle distinctly on the first 



abdominal segment ; host unknown ; Texas texana Pierce. 



2. Prothorax not arched forward ; first abdominal spiracle on the suture between 



epimeron and first abdominal segment ; host unknown ; Mexico 



mexicana Pierce. 



TRIOZOCERA TEXANA Pierce. 



Plate 64, figs. 2-10. 



This species has served to make Mengea tertiaria intelligible, as it 

 differs mainly in antennal and wing characters. Unfortunately the 

 specimen was caught at light and the head was singed, loosing its 

 antennae (the antennae in PI. I, fig. 10, are reconstructions based on 

 T. mexicana) . Otherwise the type is perfect and gives a fine under- 

 standing of the most primitive characters in the order. By tracing 

 the descriptions through the paper it will be apparent that the scutum 

 in later families has become medially separated by the backward 

 crowding of the praescutum and that the parascutellum is the result 

 of a transverse fision of scutum. Other modifications also become 

 clear. The thoracic structure of this genus is therefore given below 

 in considerable detail. 



Prothorax with notum arched forward, simple. Sternum lobate at 

 anterior angles, the lobe possibly a part of episternum. Presternite 

 tiny, triangular. Eusternum short, transverse, united laterally to 

 episternum, which is prolonged posteriorly in the form of a hook, at 

 the apex of which coxa is attached. This hook probably also contains 

 trochantin and epimeron. The sternellum (furcasternite) is medi- 

 ally divided by a strong black line, which forms an inverted T with 

 the posterior margin. The poststernellum is a tiny area behind the 

 sternellum. The remainder of the sternum is composed of soft inter- 

 segmental sldn, which extends forward into the coxal area. The 

 tiny coxa appearing like a tiny basal piece of trochanter is attached 

 to the pleural hook and by a tiny filament to a little hook at the side 

 of the sternellum. The trochanter, femur, tibia, and first tarsal joint 

 are elongate; second and third tarsal joints together about equal to 

 the first, pubescent and cylindrical; fourth joint short, inferiorly 

 lobate pulvillif orm ; fifth joint arising about the middle of fourth, 

 more slender and armed with two minutely dentate, curved ungues. 



Mesothorax with notum of a single piece faintly divided by a 

 transverse fold. The anterior part is divided by its pubescence into 

 a central area and two anterior lateral triangular pieces. The latter 

 are probably the praescutum and the central piece the scutum. 



