1956] 
Christiansen — Mesentotoma 
17 
excavate along inner distal surface. Dens and mucro. 
Dens basally with a number of short heavy ciliate setae, 
blunted apically. Mucro typical of genus. Clothing gen- 
erally as in genus Entomobrya. Large flexed clavate 
setae with expanded apex unusually large and projecting. 
Small common setae covered with short cilia along one side. 
Discussion : The “bow-like lamella” mentioned by Salmon 
requires further study before its taxonomic importance 
can be evaluated. I have found structures similar, if not 
identical, to it in many species of Entomobrya, but present 
in only a few specimens of large series. The short knob- 
like projections on the venter of the manubrium are clearly 
seen in the one specimen examined ; however, the pos- 
sibility of their being artifact, combined with the com- 
plete lack of homologous structures in the Collembola, 
has caused me to leave them out of the description until 
further series are available for examination. 
Distribution : New Zealand : Island Bay, Lyall Bay, 
Wellington (from bundles of seaweed). 
Mesentotoma dollfussi (Denis) (New Combination) 
Figs. 1-7 
Entomobrya dollfussi Denis, 1924. Ann. Soc. Ent. Fr., 
93: 232. 
Entomobrya nigrina Womersley, 1928. Ann. Mag. Nat. 
Hist., (10) 2: 63. 
Entomobrya atrata Womersley, 1929. Ann. Mag. Nat. 
Hist., (10) 4: 304. 
Color and pattern. Background color white to yellow, 
pigment blue to purple. Second and third antennal seg- 
ments apically darkened. Remainder of body with irregular 
pigmented bands and spots (see figures). Head slightly 
longer than broad. Labial appendage with external dif- 
ferentiated seta almost attaining level of apex of same 
papilla. Labral papillae truncate. Antennae with apical 
bulb of fourth segment bilobed, in a deep apical pit. Sense 
organ of third segment with two angled blunt thick setae, 
one conical guard seta. Second segment with two similar 
blunt setae more widely separated than those on third 
segment. Second segment with definite basal subsegment, 
