stough: the hackberry psylla. 156 



almost transparent. Along the median line in this space is a 

 slit, into the cephalic end of which the anus opens; this could 

 be seen in a longitudinal-vertical section, where the rectum 

 was found to run just under the dorsal surface of the posterior 

 end of the abdomen and end at the cephalic end of this slit. 

 About midway between this slit and the edges of the clear 

 space are situated the curiously ornamental openings of the 

 circumanal wax glands, outside of which are rather broken 

 and irregular rows of short, heavy, curved, sensory hairs in pits. 

 The dorsal aspect of this region of the plate is represented 

 in 31-4. This encircling band of wax glands is double; 

 their openings are ovate to rectangular, with borders measur- 

 ing 0.015 mm. in width, and are seen in the greatly magnified 

 portion shown in 26-5 B. Longitudinal-vertical sections 

 showed the glands themselves. These are of large size, flask- 

 shaped, with long necks, and are closely packed in a double row 

 under the dorsal openings. They are illustrated in section in 

 figure 5 A, wg. Their nuclei, n, could in most cases be made 

 out quite plainly. These glands are of hypodermal origin, and 

 are homologous to the circumgenital glands or spinnerets found 

 in the Coccidse. They are functional in the nymphal stages of 

 most Psyllidae, and in those forming galls the wax enters into 

 the composition of the gall, making an impervious lining for 

 the cavity, while it is found as a stringy, exuvial covering to 

 vsome of the nongall-formers. These glands are functional in 

 the nymph of Pachypsylla, but I have no evidence that they are 

 so in the adult. 



The subgenital plate is much broader and more concave than 

 the supra-anal plate, though not so long as the latter. Its 

 shape when flattened out is shown in 27-S. The anterior 

 margin is almost straight, except laterad, where it turns caudad 

 and joins the lateral margin, forming an acute angle. The 

 apex is blunt, as in the supra-anal plate. The approximate 

 measurements of the plate are: Width at base, 0.73 mm.; 

 median length, 0.63 mm.; length of lateral margin, 0.67 mm. 

 The plate is covered with rather stiff hairs, probably tactile, 

 more numerous at the posterior end and wanting at the anterior 

 end ; it is almost as heavily chitinized as the supra-anal plate. 



Ovipositor. — The insects of the suborder Homoptera possess 

 a well-developed ovipositor. This is well preserved and of 

 quite complicated structure in the family Psyllidae, 



