summer in temporary heavily shaded woodland 



pools; larvae seldom come to surface dupreei 



Gills without tracheae and much shorter than gills in 

 Fig. 148/4, at most 3 or 4 times length of anal seg- 

 ment (Fig. 138/1); lateral comb with few to many 

 scales 6 



6. Dorsal tuft at apex of anal segment represented by 



two pairs of long strong hairs ( Fig. 143/1 )• Occurs 

 in spring in woodland and bog pools. . .abserratui 

 Dorsal tuft at apex of anal segment with upper pair 

 of hairs many-branched and fanlike, Ijwer pair sin- 

 gle, long, and strong ( Fig. 1 44 A ) 7 



7. Pecten with several widely detached teeth, exemplified 



in Fig. 138/1, and extending along two thirds the 

 length of the air tube; ventral tuft situated close to 

 apex of air tube, more than three-quarters of the 

 distance from the base of air tube. Occurs during 

 summer in unshaded and usually alkaline ponds. . . 



nigromaculis 



Pecten without detached teeth and not extending so 

 far along air tube ( Fig. 145/1 ) ; ventral tuft situated 

 either midway along air tube or only two-thirds 

 distance from its base 8 



8. Lateral comb having only 4 to 6 scales; gills 3 or 4 



times length of anal segment. Occurs during sum- 

 mer in temporary woodland pools atlanticus 



Lateral comb having 10 scales or more; gills ranging 

 from 1 to 4 times length of anal segment 9 



9. Gills 3 to 4 times as long as anal segment- air tube 



thick, its length about 2.5 times its depth near mid- 

 dle (Fig. 145/1). Occurs during lats s'-iring and 

 summer, especially in temporary woodland pools 



trivittatus 



Gills only 1 to 1.5 times as long as anal seument; air 

 tube slightly more slender than that in Fig. 145/1. 

 its length equal to or exceeding 2.5 times its depth 

 near middle 10 



10. Ventral tuft of air tube situated midway along length 



of tube and composed of only 3 to 5 hairs ( Fig. 

 151). Occurs during spring in cold forest pools 



and bogs punctor 



Ventral tuft of air tube situated beyond middle of 

 tube and composed of 6 or more hairs (Fig. 152) 

 11 



11. Ventral tuft of air tube situated nearly as close to 



the last tooth of pecten as that totth is to the 

 preceding tooth; air tube at most 2.5 times as 

 long as its depth near middle (I'ig. H-I'i Occurs 



in temporary ground pools infirmatus 



Ventral tuft of air tube situated bcond the last 

 tooth ol pecten as tar as shown in Fi" '52; air 

 tube 3 or more times as long as its depth near 

 middle. Occurs during summer in temporary 

 ground pools ni'tchsllae 



12. Dorsal head hair 7, at base of ant n-;:!, delic.itc and 



single (Fig. 149B); anal segment with upper hair 

 of dorsal tuft only 2- or 3-branchcd, but nearly 

 as long as lower single hair (Fig. 149/4). An 

 introduced species that may oi, ur d-.irin,", summer 



in domestic containers around habitations; rare 



in Illinois aegj'pti 



Dorsal head hair 7 divided into a 4- to 15-branched 

 tuft (Fig. 150B>; anal segment with upper hair of 

 dorsal tuft 5- to 15-branched and much sh~rter than 

 lower single hair ( Fig. 150/4) 13 



13. Pecten with one or more apical teeth spaced fairly far 



from the nearest, appearing detached from row ( Fig. 



138/1) 14 



Pecten with all teeth close together and "orming an 

 even row ( Fig. 1 36/4 ) 2 j 



14. Air tube with pecten extending beyond ventral tuft 



(Fig. 153) 15 



Air tube with ven ral ruft situated bcyrd pecten ( F'g. 

 138/1) .' 16 



15. Air tube with about 8 hair tufts on each side ab^ve 



level of pecten (Fig. 153); lateral comb consisting 

 of 14 to 16 scales, each scale having a long apical 

 spine, as in Fig. 139/4. Occurs during spring in 

 grassy swales in light shade trichurus 



Air tube with no hair tufts other than ventral tuft: 

 lateral comb consisting of 20 to 60 scales, each scale 

 fairly evenly feathered, as in Fig. 141/4. Occurs _ 



during summer in rain-filled rock holes i 



a'npalpus 



! 6. Head hair 6 considerably to the side of, znd only slight- 

 ly anterior to, head hair 5 ( Fig. 137B ) 1~ 



Head hair 6 only slightly to the side of, but consider- 

 ably anterior to, head hair 5 ( Fig. 139B ) 18 



17. Antenna fairly thick at bas; and long, tu't beyond 



middle (Fig. 137B); head hairs 5 and 6 double, 

 occasionally 1 of the 4 head hairs triple: clypeal 

 bristles moderately far apart. Occurs during spring 



in woodland pools and bogs aurifer 



Antenna not enlarged at base, tuft below middle ( Fig. 

 13SB): head hairs 5 and 6 triple to nultiple. at 

 least 2 of the 4 head hairs with 4 to 6 branches.; 

 clypeal bristles much closer together than in aurift r. 

 Occurs during spring in woodland pools, bogs, and 

 marshes cinereus 



18. Air tube 5 times as long as its depth at middle of 



pecten. its ventral tuft very long (Fig. 140/4). Oc- 

 curs during spring in temporary woodland p<-)ols 



and bogs excrucians 



Air tube not more than 4 times as long as its depth at 

 middle of pecten. its ventral ruft frequently short 

 (Fig. 1.39/4) 19 



19. Head hairs 5 and 6 single; anal segment with only 1 



or 2 tufts anterior to ventr.il barred area at apex 

 (Fig. 147B). Occurs during spring in temporarv 



pools spenceri 



Head hairs 5 or 6, or both, double to quadruple; anal 

 segment with 3 or more nifts anterior to barred 

 area ( Fig. 1 39/1 ) 20 



20. Lateral comb consisting of 10 to 15 scales in an irregu- 



lar single or double row (Fig. 139/4). Occurs from 



spring to fall in temporary pools vexans 



Lateral comb consisting of more than 20 scales in a 

 triangul.ir patcli 21 



30 



