100 Psyche [September 
short, curving setae; posterior end of abdomen with longer curving 
setae (Fig. 29). Length 0.4 mm. White with bluish tinge mainly on 
head. 
I wish to express my many thanks and appreciation to Dr. G. F. 
Knowlton and Mr. S. C. Ma for material from Utah, to Dr. H. B. 
Mills for his notes on Xenyllodes, to Dr. H. H. Ross for material 
from Illinois, and to Dr. Hermann Gisin, Geneve, Switzerland, for 
making available specimens of Tullbergia affinis Borner from 
Europe. 
Explanation of Plate 5 
Tullbergia knowltoni, n. sp. (Figs. 1-9) 1. Dorsal view of the whole an- 
imal. 2. Ocellus. 3. Postantennal organ. 4. Tip of fourth antennal segment. 
5. Organ of third antennal segment. 6. Mandible. 7. Posterior end of ab- 
domen showing anal horns. 8. Unguis. 9. Ventral view of posterior end 
of abdomen. Polsomia highlandia, n. sp. (Figs. 10-17) 10. Hind foot. 
11. Organ of third antennal segment. 12. Dorsal surface of manubrium. 
13. Eyes and postantennal organ. 14. Tenaculum. 15. Dens-mucro 15. Dor- 
sal surface of head. 17. Pigmentation of body segment, dorsal surface 
scheme. Onychiurus wilchi, n. sp. (Figs. 18-25) 18. Dorsal view of whole 
animal. 19. Organ of third antennal segment. 20. Postantennal organ. 
21. Hind foot. 22. Ocellus. 23. Anal horn. 24. Clothing arrangement of 
setae. 25. Mandible. Xenyllodes armatus Axelson. (Figs. 26-30) 26. Eyes 
and postantennal organ. 27. Antenna showing round knob at tip. 28. Hind 
foot. 29. Posterior end of body, dorsal view, showing anal horns. 30. Dens- 
mucro. 
