170 
IOWA ACADEMY OF SCIENCES. 
EXPLANATION OP PLATES*. 
PLATE XV. 
Figures I, 2, 3. — Different stages of the larva of Apbalara polygoni, 3 
representing the pupa. 
Figures I, 5, 6. — Different stages of the larva otAphalara exilis var. 
rumicis, 6 representing the pupa; a, anterior lobes of head showing the 
wax-hairs; b, second tarsal joint showing claws and adhesive disk; c, part 
of the tip of the abdomen showing the wax-hairs. 
Figure 7. — Young larva of Trioza salicis. 
Figure 8. — Pupa of Trioza salicis; d, edge of wing-pad showing wax- 
hairs; e, tip of abdomen showing wax-hairs. 
Figure 9. — Central nervous system of larva of Psylla amorphas (third or 
fourth stage); c. b., central body; m., mushroom-shaped body; m. L, middle 
lobe; o. m., outer medulary layer; e. s., eye swelling; c. e., compound eye; 
at. L, antennal lobes; £ L, frontal lobes; ce. , oesophagus; s. g., sub-oesoph- 
ageal ganglion; s. s. indicates the location of what Dr. E. Witlaczil desig- 
nates as the sack containing the setae; th. g., thoracic ganglion showing 
four distinct parts, of which 1, 2 and 3 represent the ganglia for the three 
divisions of the thorax respectively, and 4 the ganglion from which arise 
the abdominal nerves. 
The drawing was made from a dorsal view of the larva named above. 
The parts named were determined by comparison with figures in Dr. E. 
Witlaczil’s paper on “Die Anatomie der Psylliden,” and the brief review 
of the same paper by Prof. G. Macloskie in Amer. Nat., Vol. XX, p. 283. 
Some of the parts were quite puzzling, especially the lobe between the 
middle lobe and the outer medulary layer. It is indicated in Dr. Witlaczil’s 
paper, plate XXI, figs. 39 and 40, but apparently not named. Also the 
parts designated as antennal lobes and frontal lobes. It seems as though 
they would be more on the front part of the brain and not visible from 
above. But as the larva is so fiat and all the parts of the head not so dis- 
tinctly developed as in the adult, it is likely that these lobes are located 
backward and upward from what they are in the adult, thus bringing them 
more nearly into the same plane with the other lobes indicated, and making 
them visible from above. They may, however, indicate entirely different 
parts. Further research during the larval stages is necessary to deter- 
mine that point. 
Figure 10. — Edge of abdomen of Psylla amorphas, showing the peculiar 
development of the marginal wax-hairs. 
PLATE XVI. 
Figure 1. — Wings of Psylla carpini, Fitch. The veins of the front wings 
are usually designated as follows: a, basal portion of costa, which con- 
tinues clear around the wing as a marginal vein; b, stigmal portion of costa; 
c, basal portion of the subcosta; d, discoidal portion of subcosta; e, radial por- 
tion of subcosta; pt, pterostigma; r, radius; p. c., petiolus cubiti; c^, stem of 
^Miss Charlotte M. King did the pen work on the drawings. All the figures are 
much enlarged ; the natural size of some of them being indicated by the lines at the 
side of the figure. Those in plate xv drawn from measurements, 7 and 8 being drawn on 
a little larger scale than the preceding, and 9 and 10 much more enlarged. Those on 
nlates xvi and xvii are camera drawings. 
