COLLEMBOLA OF THE FAMILY ISOTOMIDAE 69 



AGRENIA BIDENTICULATA (Tullberg) 



Plate 15, Figures 156-159 



Isotoma bidenticulata Tullberg, 1876, p. 35. — Stuxberg, 1887, p. 42. — Mac- 

 GiLLiVRAT, 1891, p. 273; 1896, p. 50.— Schaffer, 1894, p. 129.— Schott, 

 1894, p. 67. — vox Dalla Torre, 1895, p. 10. — Scherbakov, 1899a, p. 47; 

 1899b, p. 5.— Wahlgren, 1899b, p. 337; 1906a, p. 224; 1906b, p. 257.— 

 Carpenter, 1900, p. 274.— Skorikow, 1900, p. 205. — Agren, 1904, p. 17. — 

 Evans, 1908, p. 200. 



Isotoma lanuginosa Carl, 1899, p. 307. 



Agrenia bidenticulata Borner, 1906, p. 171. — Linnaniemi (Axelson), 1907, 

 p. 74; 1909, p. 9; 1912, p. 173.— Carpenter, 1908, p. 176.— Handschin, 

 1919, p. 77; 1924a, p. 116; 1924b, p. 85; 1929, p. 71.— Wahlgren, 1919, 

 p. 751; 1920, p. 8. — Carpenter and Phillips, 1922, p. 15. — Schott, 1923, 

 p. 13.— Denis, 1924b, p. 231; 1925, p. 145.— Remy, 1928, p. 65. 



Description. — Coloration variable; purple or green with pale legs 

 and furcula; or yellowish green, brownish dorsally; sometimes dark 

 brown with more or less of a greenish luster. A median dorsal black 

 spot occurs behind the eyes; anteriorly a transverse black band con- 

 nects the eye spots ; or instead of this there may be three black spots ; 

 one immediately behind the base of each antenna, and a median spot ; 

 these spots being less evident in heavily pigmented individuals. 

 Eyes (pi. 15, fig. 156) eight on each side, on black spots, the two inner 

 proximal eyes much smaller than the others. Postantennal organ 

 (pi. 15, fig. 156) roundish, oval or broadly elliptical, slightly longer 

 than the diameter of the adjacent eye. Antennae almost or quite 

 twice as long as the head, with segments in relative lengths about as 

 11:13:15:19. Sense organ of third antennal segment (pi. 15, fig. 157) 

 with two curving rods, usually freely exposed. Fourth antennal seg- 

 ment with small olfactory setae, three ventroapical finely granidate 

 papillae, and a subapical pit with a central tubercle. Unguis (pi. 15, 

 fig. 158) long and narrow, with a small tooth near the middle of the 

 inner margin, and' a pair of large basal lateral teeth, between which a 

 delicate membrane extends closely over the base of the unguis. Unguic- 

 ulus two-fifths to one-half as long as the opposite unguis, with a pair 

 of inner lamellae. Tibiotarsus without a distal subsegment and with- 

 out tenent hairs or other long distal hairs. Third and fourth abdom- 

 inal segments subequal, or tliird a trifle longer than the fourth (as 

 25:24). Genital and anal segments ankylosed. Furcula appended to 

 the fifth abdominal segment and attaining the ventral tube. Man- 

 ubrium with abundant short stiff ventral setae. Dens almost or quite 

 twice as long as manubrium, subcylindrical, slightly narrowing dis- 

 tally, not rounded apically, not crenulate, but dorsally covered with 

 small rounded turbercles; dorsally with a few short proximal setae; 

 laterally and ventrally with abundant stiff' setae. An exceptionally 

 long and strong subapical seta on the mesal side of the dens extends 

 far beyond the mucro (pi. 15, fig. 159). Mucro (pi. 15, fig. 159) 

 about one-third as long as liind imguis, bilamellate, with strongly 



