1950 ] 
Wray — Nearctic Collembola 
97 
rather moist due to the very heavy yearly rainfall making it ideal 
for collembolan fauna. Cotypes in author’s collection. 
Family Poduridae. 
Genus Tullbergia Lubbock. 
Tullbergia (Mesaphorura) knowltoni, n. sp. 
(Figs. 1-9) 
Length up to 0.7 mm. White. Slender (Fig. 1), body five times 
as long as broad. Antennae short, two-thirds as long as head, the 
third and fourth segments not distinctly separated. Relative lengths 
of antennal segments as: 3:4:6:5. Antennal base well developed. 
Fourth antennal segment with a terminal sense knob and with 6 to 8 
large, curving olfactory setae (Fig. 4). Organ of third antennal 
segment (Fig. 5) with three guard setae, two large sub-reniform 
sense clubs, curving toward each other, and two large papillae 
shielding the sense clubs ; ventro-laterally to these is an auxilliary 
sense club. Postantennal organ in an elongated groove, with about 
24-28 irregular tubercles (Fig. 3), somewhat shaped like the Ony- 
chiurus fimetarius group postantennal organ. Pseudocelli, rosette- 
like, situated on each side as follows : 1 between postantennal organ 
and base of antenna, 1 on posterior part of head, 1 on mesothorax 
and metathorax, and with 1 on abdominal segments I-V, wanting 
on abdominal segment VI. 
Unguis (Fig. 8) unarmed. Unguiculus absent. Anal horns (Fig. 
7) 3 ; two long, strongly curved ones about twice the length of the 
hind unguis are situated on the postero-dorsal end of body on large 
nearly contiguous papillae ; the third horn is short, bluntly rounded 
at apex, in length about half the unguis, and is situated mid-ventral 
to the pair above. 
Body with short backward curving setae in three rows on meso- 
thorax to abdominal segment V. Longer setae intermingled in one 
row on each segment and are more abundant on head and 5th and 
6th abdominal segments. The 6th abdominal segment with two rows 
of long curving setae. Integument granulate, becoming coarser dor- 
sally on the posterior margin of thorax II to abdominal segment V. 
Logan, Utah, October 31, 1949, G. F. Knowlton and S. C. Ma. 
Taken in honeysuckle leaves by means of a modified Berlese fun- 
nel. Cotypes at present in author’s collection. 
