22 
Psyche 
[March 
Ventral tube with about eight ventral setae. Rami of 
tenaculum quadridentate ; corpus with one seta. 
Manubrium ventrally with two pairs of strong setae near 
the distal margin. Dens twice length of manubrium ; dorsal- 
ly crenulate in the middle third only, with about 16 folds; 
bearing a few fine setae dorsally and many ventrally. Mucro 
(fig. 5) bidentate, the apical tooth much the larger and 
strongly curved; a medial lamella runs to the tip of the 
proximal tooth. 
Fifth and sixth abdominal segments wholly ankylosed. 
Female genital opening a transverse slit, with anterior and 
posterior lips each bearing a pair of setae. Male genital 
opening not seen. 
Pigment wholly absent, except for the amber-colored 
mouth parts. 
Length of holotype 0.65 mm. Range (12 specimens) 0.4 
to 0.75 mm. The relative proportions of the segments may 
be judged from fig. 9; unfortunately specimens tend to be 
somewhat distorted in mounting, and the normal propor- 
tions cannot be determined. 
The number of sensory hairs on the fourth antennal seg- 
ment varies from eight to eleven. The number of serrate 
setae varies somewhat also, but these are easily detached 
and part of the variation may be apparent only. In one 
specimen one ramus of the tenaculum is quinquedentate. 
Holotype: “Cathedral Pines”, Cornwall, Litchfield Co., 
Explanation of Plate 2 
Micrisotcma achromata. Magnifications approximate. Fig. 1. Dorsal 
view of left fourth antennal segment, holotype (700 X) . Fig. 2. Right 
postantennal organ, partype (700 X) . Fig. 3. Right postantennal organ, 
paratype, transverse optical section (700 X) . Fig. 4. Left hind claw and 
distal part of tibiotarsus, holotype (700 X). Fig. 5. Left mucro and end 
of dens, paratype (700 X) . Fig. 6. Serrate seta from second abdominal 
segment, holotype (700 X) . Fig. 7. Blunt seta from sixth abdominal 
segment, holotype (700 X). Fig. 8. Fused fifth and sixth abdominal 
segments showing arrangement of setae; somewhat diagrammatic 
(350 X). Fig. 9. Holotype; outline, setae omitted. (120 X). 
