58 BULLETIN 168, UNITED STATES NATIONAL MUSEUM 



Manubrium setigerous dorsally; with three ventral subapical setae. 

 Several long stiff erect simple setae occur dorsally on the manubrium 

 and the bases of the dentes. Dentes (pi. 21, fig. 232) shghtly shorter 

 than manubrium, stout, with eight to ten coarse dorsal crenulations. 

 At the extremity of the dens is a large lateral transparent bladderlike 

 dilatation (pi. 22, figs. 233, 234) extending beyond the mucro. Mu- 

 crones (pi. 22, figs. 233, 234) stout, subequal to hind unguiculi in 

 length, tridentate; apical tooth the smallest, more or less hooked; 

 second and third teeth in line with the first, subequal or third smaller 

 than second, suberect or inclined shghtly forward. Ventral margin 

 of mucro well rounded, in lateral aspect. Rami of tenaculum triden- 

 tate; corpus with two stout curving ventral setae. General clo tiling 

 (pi. 22, fig. 235) of short stout curving simple setae of uniform length; 

 erect sensory setae short, stout, simple; several long stout simple 

 setae occur dorsally on the last two abdominal segments. The 

 integument is smooth externally but the intersegmental membranes 

 of the body are reticulate (figs. 236, 237), as are also the antennae, 

 legs, furcula, and the ventral integument of head and body. Length, 

 1.3 mm. 



Cotypes.—V.^.NM. no. 42983. 



Remarks. — The only examples of this species that I have seen are 

 the cotypes, taken at Arnprior, Ontario, December 7 and 8, on snow, 

 by Charles Macnamara. 



PROISOTOMA (PROISOTOMA) BULBOSA. new species 



Plate 22, Figures 238-244 



Descrii)tion.- — Blackish blue, including the appendages. A stout 

 species. Eyes (pi. 22, figs. 238, 239) eight on each side, one or both 

 of the inner proximal eyes on each side being smaller than the others. 

 Postantennal organ (pi. 22, figs. 238, 239) subelliptical but somewhat 

 irregular, twice as long as the diameter of an adjacent eye, with an 

 exceptionally thick bordering ridge. Antennae shghtly longer than 

 the head (as 7:6), with segments variable in relative lengths; third 

 segment usually a little shorter than the second, occasionally a httle 

 longer; fom*th two to three times as long as second. Sense organ of 

 third antennal segment (pi. 22, fig. 240) with a pair of feebly curving 

 rods in a deep groove, with four guard setae. The curving setae of 

 the fourth antennal segment are strong, but not evidently tlifleren- 

 tiated as olfactory setae. Tibiotarsi not subsegmented. Unguis 

 (pi. 22, fig. 241) weakly curving, with a pair of lateral teeth two- 

 fifths from the base, and an inner tooth one-third from the apex. 

 Unguiculus extending three-fifths to four-fifths as far as the unguis, 

 sublanceolate, acute, untoothed. One tenent hair, weakly knobbed. 

 Third abdominal segm.ent shorter than the fom-th (about as 19:22). 

 Genital and anal segments ankylosed, with the dorsal suture often 

 indicated, however; dorsally with coarse tuberculate ridges. Furcula 



