Pomona College Journal of Entomology 



848 



not reaching ventral tube; not slender and tapering. Manubrium slightly 

 longer than dentes and mucrones together; fine serrations on dorsal edge of 

 dentes; sparsely haired. Muerones (Figure 26!), H) bidentieulate; first tootii 

 horizontal, long, .slender, eurving but .slightly; .second tooth vorticiil and 

 curves slightly cephalad. 



Habitat — Nova Zembhi, Northern Siberia, and Greenland. 



Figure 269. Isotoma bidenticula Giitli. 

 \ tarsus witli two claws; B, mucrones: C. antenna; D, eyes of one side; E, post- 

 ' ' ' ■ ' antennal organ; F, furcula. 



Isotoma besselsii (Packard) 



(Figure 270) 



Very few of these specimens were found. In general appearance they 



look almost exactly like the /. biilciificula. although slightly smaller. These 



were hard to identify a.s they resembled both the Isotoma inininia (Guthrie) 



