84 



The Irish Naturalist. 



May, 



years (see Theobald, 'lo, pp. ni-127). It is certainly 

 remarkable that an insect new to science should have been 

 discovered for the first time in such enormous numbers. 





Fig. I, Pruisoioma ultonica, side view, x 60; tig. 2, ocelli and post- 

 antennal organ of right side, X 350 ; fig. 3, foot with claw and empodial 

 appendix, X 600; fig. 4, catch, x 600; fig. 5, spring, dorsal view, 

 X 60 ; fig. 6, dens and niucro of spring, side view, x 350. 



A few years ago, this springtail would have been included 

 in the comprehensive genus Isotoma. Now, the six distinct 

 abdominal segments, the simple sensory bristles, the short 

 spring with relatively large or elongate mucro, characterize 

 the genus Proisotoma of Borner ('03, p. 171). We already 

 know P. Schotti (Dalla Torre) from the west coast of Ireland, 

 and the species of Proisotoma have a curious and interesting 

 discontinuous range in the Arctic Regions, the British Isles, 

 North and South America, and the Antarctic. 



