COLLEMBOLA OF THE FAMILY ISOTOMIDAE 91 



"They were in small piles or swarms lying on the ground. Could 

 have secured a gallon of them." 



Additional specimens numbering thousands of individuals were 

 sent to me from Alabama by Prof. J. M. Robinson. 



Cotypes.— U.S. ISIM. no. 42968. 



Distribution. — Recorded as follows: 



Illinois: Marissa, June 24, T. Keyworth. 

 Kansas: Kiowa, June 18, J. M. Miller. 

 Alabama: Auburn, March 25, J. M. Robinson. 



ISOTOMA (ISOTOMA) TRISPINATA MacGillivray 



Plate 29, Figures 331-336 

 Isotoma trispinata MacGillivray, 1896, p. 51. 



Description. — General color grayish or bluish; blackish when heavily 

 pigmented ; finely mottled with blue pigment; with pale intersegmental 

 bands. The posterior border of the head, and the mesonotum and 

 metanotum, are narrowly edged with blue, as are also the posterior 

 borders of the abdominal segments. Head with an anteocular 

 blackish A-shaped mark; antennae bluish; legs and furcula white, 

 shghtly pigmented basally. Eye spots black, large, midway between 

 antennae and base of head. Eyes (pi. 29, fig. 331) eight on each side, 

 slightly unequal. Postantennal organ (pi. 29, fig. 331) close to eyes, 

 oval, one and one-half to two times as long as the diameter of an 

 adjacent eye. Antennae longer than the head (as 4:3) with segments 

 in relative lengths about as 15:25:27:42; second and third segments 

 subclavate; fourth stout, elliptical, without special olfactory setae. 

 Third abdominal segment shorter than the fourth (as 3:4 or 4:5). 

 Genital and anal segments not ankylosed. Unguis (pi. 29, fig. 332) 

 stout, simple, without teeth. Unguiculus extending two-thirds as 

 far as the unguis on the hind feet, relatively large, broadly lanceolate, 

 acuminate, with inner basal margin strongly rounded and untoothed ; 

 shorter on fore and mid feet. Tenent hairs absent. Furcula appended 

 to the fifth abdominal segment, extending to the anterior border of 

 the ventral tube. Dorsal setae of manubrium numerous, short and 

 erect; ventral setae numerous, stiff, and inclined backward. Dentes 

 more than twice as long as manubrium, slender, tapering, finely 

 crenulate dorsally; the crenulations ending at a distance from the 

 mucro equal to one and one-half times the length of the latter; ven- 

 trally with many short stiff obUque setae, and with a strong subapical 

 seta extending as far as, or beyond, the end of the mucro. Mucrones 

 (pi. 29, figs. 333-336) minute, slightly longer than hind unguiculus, 

 with strongly rounded ventral margin, tridentate; apical tooth large, 

 upcurving; anteapical tooth smaller, conical, erect or oblique; third 

 tooth proximal, ventrolateral, oblique, acute. Rami of tenaculum 

 quadridentate; corpus with several (5 to 7) curving setae. Clothing 



