COLLEMBOLA OF THE FAMILY ISOTOMIDAE 35 



Remarks. — In this species the achorutoid (see pp. 4-5) characters 

 of the genus Guthriella are especially pronounced. 



G. antiqua occurred in great abundance in a depression in a creek 

 bed where the water had dried up. 



(7o/ypcs.— U.S.N.M. no. 42995. 



Distribution. — Recorded as follows: 



Missouri: Mountain Grove, March 29, E. P. Taylor. 



GUTHKIELLA VETUSTA, new species 



Plate 10, Figures 100-106 



Description. — General color blacldsh blue; head and body with 

 close minute round pale spots and larger pale spots, rounded or 

 elongate. Pigment deep blue; antennae blue; praecoxae and coxae 

 dark blue; remaining leg segments more or less strongly pigmented; 

 manubriiun blue; dentes unpigmented, yellow in alcohol, possibly 

 wliitish in life. Prothorax heavily pigmented, tuberculate. Body 

 and appendages stout. Body segments strongly bulging, with deep 

 intersegmental constrictions. Eyes (pi. 10, fig. 100) on black patches, 

 eight on each side, the two inner proximal eyes much smaller than the 

 others. Postantennal organ (pi. 10, fig. 100) remote from eyes, near 

 base of antenna, elliptical, one and one-half times as long as the dia- 

 meter of an adjacent eye. Antennae shorter than the head (as 7:8) or 

 subequal to it, with segments in relative lengths about as 10:17:15:25. 

 First antennal segment cyHndrical, second subclavate, third clavate, 

 fourth elliptical. Sense organ of third antennal segment (pi. 10, 

 fig. 101) with a pair of free subcyhndrical rods and three guard setae. 

 Fourth antennal segment with short stout cm'ving olfactory pegs. 

 Abdominal segments without ankylosis; fourth segment longer than 

 the third (as 3:2). Tibiotarsus with a distal subsegment. Unguis 

 (pi. 10, fig. 102) slender, not strongly curving, wdthout lateral or 

 inner teeth. Unguiculus extending two-thirds as far as the unguis on 

 the hind feet; one-half as far on the other feet; sublanceolate, 

 acuminate, untoothed, with a pair of inner lamellae. Tenent hairs 

 two or three, as long as ungues. Furcula appended to the fifth 

 abdominal segment, extending not quite to the second. Manubrium 

 short and stout, naked ventrally, with a few stift' setae dorsally, and 

 with a pair of subapical hooks. Dentes (pi. 10, fig. 103) longer than 

 manubrium (as 3:2) or subequal to it, subcyhndrical, narrowing 

 but slightly, not rounded apically, with only the usual cuticular 

 tubercles dorsally, with 9 or 10 dorsal setae, and naked ventrally. 

 Mucrones (pi. 10, figs. 104, 105) one-fifth to one-fourth as long as 

 dentes, bidentate, bilamellate; both teeth erect, the apical tooth 

 being the smaller; lamellae equal, extending on each side from the 

 anteapical tooth to the base of the mucro. Rami of tenaculum 

 quadridentate ; corpus with two anterior setae. General clothing of 



