COLLEMBOLA OP THE FAMILY ISOTOMIDAB 47 



mented. Unguis (pi. 17, fig. 171) exceptionally long and slender, 

 curving, without lateral teeth, with a minute inner tooth (which may 

 be absent) about one-third from the apex. Unguiculus (pi. 17, fig. 

 172) broad basally, acute, untoothed, with a pair of inner lamellae; 

 on first feet, one-third as long as unguis; on second and third feet, two- 

 fifths as long. Tenent hairs absent, represented by a very long 

 simple hair. Furcula pale green, appended to the fifth abdominal 

 segment, attaining the ventral tube. Manubrium a little shorter 

 than dentes, densely and minutely setaceous, ventrally with many 

 short stiff setae, most numerous distally. Dentes stout, subcylindri- 

 cal, not tapering, rounded apically, neither crenulate, nor tuberculate 

 dorsally, v/ith dense short curving setae on all sides; distally with long 

 stiff setae on the mesal sides, those of one side crossing those of the 

 other. Mucro (pi. 17, figs. 173, 174) stout, equal to, or a little longer 

 than, hind unguis, tridentate and complexly lamellate. The three 

 teeth are dorsal and in longitudinal alinement, the third, or proximal, 

 tooth, being large and conspicuous. There are four lamellae (pi. 17, 

 figs. 173, 174) as follows: Dorsal, ventral, outer, and inner. The 

 dorsal lamella extends from the base of the mucro to the proximal 

 tooth {ad, anterodorsal) and from the proximal tooth to the ante- 

 apical tooth {'pd, posterodorsal) ; but this posterior portion of the 

 dorsal lamella is deeply notched just behind the proxim.al tooth, and 

 thus consists of two lobes. The ventral lamella (v) extends from the 

 base of the mucro to the apical tooth. The outer, or lateral, lamella 

 (o) extends only a little beyond the middle of the mucro. The inner, 

 or mesal, lamella {%) extends from the base of the mucro to the ante- 

 apical tooth. Rami of tenaculum (pi. 17, fig. 175) quadridentate ; 

 corpus with many curving setae. General clothing (pi. 17, fig. 176) 

 of dense short equal simple setae, slightly longer posteriorly; sen- 

 sory setae, longer than the others, outstanding, simple. Integument 

 smooth. Length, 2.3 mm (^vlassachusetts specimens). 



Young individuals that I received from New York State are purple 

 above, white intersegmentally, with yellow head, purple antennae, 

 purplish- white legs, and white furcula. 



In specimens from Illinois the anterior body segments are dark 

 purple, and the last four abdominal segments and the head ohve- 

 green. 



Remarks. — This species was determined for me by Dr. C. Schaffer, 

 to whom I once sent specimens collected in Massachusetts. 



I formerly found this to be a common species in eastern Massa- 

 chusetts on ponds and brooks and in sphagnum moss — always in wet 

 situations. It skips about in a lively manner on water, owing its 

 ability as a leaper to its strong furcula, which, like that of Podura 

 aquatica, is structurally adapted for use on the surface of water. 

 The dense bristles of the furcula, the long stiff crossing mesal setae 

 of the dentes, and particularly the highly developed lamellae of the 



