62 COLLEMBOLA OF MINNESOTA 



O. albosa. Antennae slender and hairy, about three times as 

 long as the head. Ant. Ill is yellow with the faintest possible 

 tinge of blue in a spot at the distal end in some of the darker 

 specimens. IV and V have each about the distal halves dark 

 blue, VI shades out distally from yellow to a dead, blackish 

 purple. While I am aware that color characters are often of 

 doubtful value, yet the species at hand varies so little in the 

 scores of specimens examined, that I believe an antenna alone 

 would serve to identify it. 



The body is thickly covered with short hairs, some longer 

 ones appearing on Abd. V and on the furcula, also bunches of 

 long, clubbed hairs on dorsal parts of head and thorax. The 

 claws are of the ordinary Orchesella type long and slender, 

 the inner claw narrow lanceolate, with a small outer tooth, the 

 outer claw with an outer and two inner teeth. The tibia bears 

 one clavate hair. 



The whole furcula is very hairy, two or three feather-like 

 hairs project from dentes beyond mucrones, the longest pro- 

 jecting over by nearly the length of the mucrones. Manubrium 

 slightly arcuate, dentes slender, slightly longer than manubri- 

 rm, arcuate, serrulate beneath. 



Mucrones small, tridenticulate ; the apical tooth curved, 

 acute, the next stouter; proximal tooth very islender and point- 

 ing towards the tip of the next tooth, it stands on the outer lat- 

 eral side of mucrones. 



The antennae seem quite subject to mutilation, and one 

 finds many different forms in consequence. Figures I2a and I2b 

 show two such antenna?. Lubbock's experiments upon the an- 

 tennas of O. cincta, as recorded in his notes on the Thysanura, 

 Part IV, p. 285, show that when an antenna is mutilated by the 

 loss of one or more segments the terminal remaining seg- 

 ment elongates often far beyond its norm, coming to resemble 

 the normal Ant. VI in form; but that no new segments are 

 formed. Thus in figs. a and b, which were found on the same spec- 

 imen, and were of equal length, a had lost only Ant. VI, or 

 possibly in addition a part of Ant. V, while the long distal seg- 

 ment on b is Ant. Ill, which is normally very short. Perhaps 

 we might better say that the distal segment is not merely the 

 third, but essentially all the segments from the second one out. 



