NO. 2134. NORTH AMERICAN COLLEMBOLOUS INSECTS— FOLi:;OM. 497 



from the base, and without a lamella. Anal spines (fig. 147, 148) 

 two, minute, about one-fourth as long as hind unguis, feebly curving 

 forward, on low separated papillae. Clothing (fig. 149) of sparse 

 short curving setae with fewer longer and stiff setae, the largest 

 setae often being minutely serrate. Length, 1.5 mm. 



California. — Claremont, in great numbers on pools of water in a 

 newly plowed field after a rainstorm, Gertrude A. Bacon, after whom 

 the species is named. 



Cotif pes. —Cat. No. 19903, U.S.N.M. 



XENYLLA WELCm, new species. 

 Plate 18, figs. 150-157. 



Pale violet or grayish; pigment mottled. Eyes five on each side. 

 Antennae slightly shorter than the head. Sense-organ of third 

 antennal segment as in figure 150. Unguis (fig. 151) unidentate, 

 minutely tuberculate. Unguiculus represented by a rounded tubercle. 

 Tenent hairs 1,2,2, knobbed. Rami of tenaculum tridentate. Dens 

 and mucro demarcated by an articulation (figs. 152, 153); dens with 

 two setae. Mucro (figs. 153, 154) three-fifths as long as dens, 

 distally produced and curving, apically rounded; inner lamella 

 broad, terminating before the apex, minutely tuberculate. Anal 

 spines (figs. 155, 156) two, minute, separated, curving slightly 

 forward. Clothing (fig. 157) of sparse short curving setae. Length, 

 0.9 mm. 



There is some variation in the form of the mucro, as will be seen 

 from figures 153 and 154; furthermore, the tooth of the unguis is 

 sometimes absent. 



Manhattan, Kansas, January 4, in enormous numbers on mush- 

 room beds in a greenhouse. Collected b}^ Dr. P. S. Welch, after 

 whom the species is named. 



Walnut, Kansas, in immense numbers on the ground, E. P. Taylor. 



Chicago, Illinois, August 14, on walls of carnation house, J. J. 

 Davis. 



CotyiJes.— Cat. No. 19904, U.S.N.M. 



XENYLLA GRACILIS Guthrie. 



Plate 19, figs. 158-161. 



Xenylla gracilis Guthrie, 1903. 



"Rather dark blue above, paler beneath. Body slender, fusiform, 

 head narrow in front, becoming broader between the eyes and then 

 narrowing again. Thorax narrower than the head. Abdomen gradu- 

 ally broadening posteriorly till the fourth segment, after that nar- 

 rowing rather abruptly, the fifth and sixth segments being much 

 narrower. The sixth is blunt on the end, and bears two supra-anal 

 10600°— Proc.N.M.vol.50— 16 32 



