56 BULLETIN 168, UNITED STATES NATIONAL MUSEUM 



PROISOTOMA (PKOISOTOMA) BREVIPENNA (MacGlllivray) 



Plate 21, Figures 223-225 

 Isotoma brevipenna MacGillivray, 1896, p. 53. 



Description. — Dark purple, mottled with small pale spots; antennae, 

 legs, and furcula paler. Eyes and postantennal organs, not studied. 

 Antennae slightly shorter than the head, with segments in relative 

 lengths about as 2:3:3:8. First two segments cylindrical, tliird 

 gradually dilating apically, fourth elliptical. Body stout. Third 

 abdominal segment shorter than the fourth (as 13:18). Genital and 

 anal segments ankylosed, with an obsolete dorsal suture. Unguis 

 (pi. 21, fig. 223) largest on the hind feet, comparatively slender, 

 curving, with a pair of strong lateral teeth, and inner margin uni- 

 dentate about one-tliird from the apex. Unguiculus lanceolate, 

 acuminate, unidentate. Tenent hairs 1, 2, 2. Furcula appended to 

 the fourth abdominal segment, short, not reaching the ventral tube, 

 but extending about to the middle of the third abdominal segment. 

 Manubrium longer than dentes (as 4:3). Dentes stout, swollen, 

 tapering gradually, rounded apically. Mucro (fig. 224) as long as hind 

 unguiculus, stout, tridentate; apical tooth small, hooked; second and 

 third subequal, inclined sUghtly forward; ventral margin in lateral 

 aspect almost straight except distally. Corpus of tenaculum with 

 several curving setae. General clotliing (pi. 21, fig. 225) of dense 

 short curving setae; sensory setae long, outstanding. Length, 1.5 mm. 



Remarks. — The preceding description, in some respects incomplete, 

 was made from a single type in the ISIuseum of Comparative Zoology, 

 Cambridge, Mass., taken at Salineville, Ohio, by A. D. MacGiUivray. 



PROISOTOMA (PROISOTOMA) ODSOLETA (MacGillivray) 



Plate 21, Figures 226-228 



Isotoma obsoleta MacGillivray, 1896, p. 54. 



Description. — Blackish violet. Eyes eight on each side, unequal, 

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

 Postantennal organs situated near the bases of the antennae, narrowly 

 elliptical, with thick wall, and about twice as long as the diameter of 

 an adjacent eye. Antennae slightly longer than the head, with 

 segments in relative lengths about as 4:5:G:12; second and third 

 segments dilated apically. Third abdominal segment shorter than 

 the fourth (as 6:7). Genital and anal segments ankylosed. Tibio- 

 tarsus without a distal subsegment. Unguis (pi. 21, fig. 226) stout, 

 strongly curving, with a pair of small lateral teeth, without an inner 

 tooth. Unguiculus more than half as long as unguis, broadly lanceo- 

 late, aciculate, with a strong inner tooth (sometimes absent). Tenent 

 hairs absent; represented by a single long simple hau\ Furcula 

 short, extending only about as far as the middle of the third abdominal 

 segment. Dentes longer than manubrium, stout, subcylindrical, 



