COLLEMBOLA OF THE FAMILY ISOTOMIDAE 49 



other. On my single specimen a minute proximolateral fifth tooth 

 occurs on the left mucro but not on the right. Rami of tenaculum 

 quadridentate ; corpus with a few ventral setae (four observed). 

 General clotliing of dense short curving setae; sensory setae longer, 

 curving, becoming still longer and more numerous on the last three 

 abdominal segments. Antennae densely clothed with short curving 

 setae interspersed with long stiff setae. Integument smooth. Length, 

 1.5 mm. 



Remarks. — This description was made from one cotype, given to mo 

 by Dr. MacGillivray, taken by him at Salem, Ohio. 



PKOISOTOMA (PROISOTOMA) TITUSI, new species 



Plate 18, Figures 181-189 



Description. — Dark purple, with many rounded pale spots. An- 

 tennae, legs, and manubrium purphsh. Eyes (pi. 18, fig. 181) eight 

 on each side, subequal. Postantennal organ (pi. 18, fig. 181) elon- 

 gate, three to five times as long as the diameter of an eye, four or five 

 times as long as broad, usually sh'ghtly constricted near the middle. 

 Antennae subequal to head in length, or a trifle longer, with segments 

 in relative lengths about as 8:11:9:18. Sense organ of third antennal 

 segment (pi. 18, fig. 182) with a pair of subclavate curving rods under 

 a cuticular fold, and an accessory pair of hnear rods. Fourth antennal 

 segment with long olfactory setae. Prothorax pigmented, not greatly 

 reduced; terga of remaining segments imbricate. Tibiotarsus with a 

 distal subsegment. Unguis (pi. 18, fig. 183) slender, curving, vrith- 

 out lateral teeth, with a weak tooth near the middle of the inner mar- 

 gin. Unguiculus extending three-fifths as far as unguis on hind feet, 

 broadly lanceolate, acuminate, untoothed, wdth a pair of inner lamel- 

 lae. Tenent hairs 1, 2, 2. Genital and anal segments ankylosed, 

 with an obsolete dorsal suture. In young individuals the dorsum of 

 the fifth abdominal segment bears numerous tuberculate protuber- 

 ances, as in plate 18, figure 184; in old individuals only traces of these 

 remain. Fourth abdominal segment slightly longer than the third 

 (as 14:13). Furcula appended to the fifth abdominal segment, not 

 attaining the ventral tube, but extending to the middle of the second 

 abdominal segment, gradual!}^ tapering. Manubrium with many 

 strong dorsal setae and with one pair of ventral subapical setae. 

 Dentes four-fifths as long as manubrium, rather stout proximally 

 (fig. 185) but gradually narrowing from base to apex, coarsely crenu- 

 late dorsally, there being about five large proximal folds and ten 

 smaller distal folds; dens with long dorsal and ventral setae. Mucro 

 (pi. 18, figs. 186-188) short and stout, about as long as hind unguicu- 

 lus, tridentate, bilamellate ; apical tooth longitudinal, curving upward 

 apically; anteapical tooth subequal to first or larger, suberect; tliird 

 tooth lateral, close to second tooth and shghtly more proximahthan 

 the latter, curving. The inner lamella extends from the base of the 



