62 BULLETIN 168, UNITED STATES NATIONAL MUSEUM 



numerous dorsal crenulations, which are coarse proximally and finer 

 distally, with stiff ventral setae and a few outstanding dorsal setae. 

 Mucro (pi. 23, fig. 258) bidentate; apical tooth smaller than the ante- 

 apical. Rami of tenaculum quadridentate ; corpus with a single seta. 

 General clothing of short simple setae; erect sensory setae short, 

 simple. Integument smooth. Maximum length, 1.1 mm. 



Cotypes.—V.S.'NM. no. 42976. 



Distribution. — Recorded as follows: 



Pennsylvania: Kennett Square, in a mushroom house. Concordville, September 

 24, in a manure pile, C. A. Thomas. 



PBOISOTOMA (PROISOTOMA) TENELLOIDES, new species 



Plate 23, Figures 259-261 



Description. — General color grayish or blackish, with close pale 

 spots of various sizes. Pigment black, in the form of minute granules, 

 which outline the hypodermis cells. Intersegmental regions banded 

 narrowly with white. Head Anth a dark interocular area containing 

 minute round pale spots, uniform in size and distribution. Antennae 

 stout; segments spotted wdth blackish pigment; first three segments 

 unpigmented basally. Coxae pigmented ; legs otherwise white. Fur- 

 cula white, with a little dorsal pigment at the base of the manubrium. 

 Eyes eight on each side, equal. Postantennal organ (pi. 23, fig. 259) 

 large, subelliptical, constricted at the middle, with wide border, and 

 three times as long as the diameter of an eye. Antennae stout, a 

 little longer than the head, with segments about as 12:17:14:29; 

 third segment thus slightly shorter than the second, and fourth twice 

 as long as the third. Sense organ of tliird antennal segment present, 

 of the usual type. Fourth antennal segment without special olfactory 

 setae. Third urotergite shorter than the fourth (as 4:5 or 6:7), Gen- 

 ital and anal segments ankylosed. Tibiotarsus and femur each with 

 a distal subsegment. Unguis (pi. 23, fig. 260) stout, almost straight, 

 without lateral teeth, with a small tooth near the middle of the inner 

 margin, Unguiculus extending not quite half as far as unguis on hind 

 feet, lanceolate, untoothed. One tenent hair, as long as the unguis, 

 Furcula arising betw^een the fourth and fifth abdominal segments, 

 short, extending a little beyond the posterior margin of the second 

 abdominal segment. Manubrium three-fifths as long as dentes, dor- 

 sally and laterally wdth a few short stiff setae; ventrally naked except 

 for one subapical pair of setae. Dentes ventrally with relatively few 

 short stiff setae; dorsally with numerous fine crenulations (25 to 35), 

 which are absent proximally and end distally at a distance from the 

 mucro equal to twice the length of the latter. Mucro (pi. 23, fig. 261) 

 one and one-half times as long as liind unguiculus, bidentate, with 

 both teeth directed dorsally; apical tooth larger than the anteapical; 

 ventral margin strongly rounded in lateral aspect. Rami of tenacu- 

 lum quadridentate; corpus with one long straight anterior seta. 



