COLLEMBOLA OF MINNESOTA 25 



Keys for the Determination of Orders, Families, 

 Genera and Species . 



The figures immediately following the names of the orders, 

 families, genera and species refer to the pages on which the 

 descriptions are begun. 



SUB-CLASS APTERYGOGENEA. 



a — Antennae multi-articulate. Eyes compound or wanting. 

 No ventral tube or furcula. Abdomen consisting of about 

 ten segments and terminated by long setae or forcipate ap- 

 pendages. Palpi large, projecting. Order THYSANURA. 

 b — Antennae 4-6 jointed. - Eyes of degenerate compound type, 

 with few (usually 16) ocelli, or sometimes with none. Ven- 

 tral tube invariably present, furcula typically so. Abdomen 

 consisting of six segments, and never terminated by caudal 

 setae or forcipate appendages. Palpi not evident. 



Order COLLEMBOLA. 

 Key to the Order Collembola. 

 a — Body sub-globular, abdomen little longer than broad, the 

 segments fused together. Ventral tube and furcula well- 

 developed. Scales never present. Claws two. Antennae 

 4-jointed, no post-antennal organ. 



Family Sminthuridae, 25. 

 b — Body sub-cylindrical, segments of abdomen free. Furcula 

 usually on penultimate segment. Scales present or absent. 

 Antennas 4-6-jointed. Claws two. 



Family Entomobryidae, 29. 

 c — Body sub-cylindrical, segments of abdomen free, body 

 without scales (in any of our species). * Furcula present, 

 on antepenult. Antennae 4-jointed. Claws 2 or i. 



Family Poduridae, 37. 

 d — Body sub-cylindrical, segments of abdomen free. Furcula 

 wanting. Body naked or hairy, never with scales. Anten- 

 nae 4-jointed, often poorly developed. Claws 2 or i. 



Family Aphoruridae, 40. 

 Family Sminthuridae. 

 This family seems to have pretty well defined limits, and its 

 species are not likely to be confused with those of other fani- 



