nliY. 



k^. Cuticle near head thicker than spear width 



,,.,, callosus Skwarra, 1921 (s) 



Cuticle near head thinner than spear width Ii6 



i|6. Esophagus expanded before the middle U7 



Esophagus expanded in posterior half U9 



klm Body width over 3. 5^ crassus de Man, l88it (a or s) 



Body width 2.$— 3.0$ hQ 



U8« Spear one-third as wide as lip region . . merogaster Steiner, 1916 (a) 

 Spear one-fourth as wide as lip region 

 prolificus Th. & Swang., 1936 (a) 



k9» Lips continuous with neck contour . . . . flexus Th. & Swang., 1936 (a) 

 Lips set off by a depression $0 



50. Width 2.0$ or less pseudostagnalis l^Iicol., 1927 (a) 



Width near U.0$ crassoides Jagersk., 1908 (a) 



51. Lip region definitely set off by constriction or expansion 52 



Lip region not set off by constriction or expansion . 5U 



52. Lip region broadly expanded; width 1.5$ . . attenuatus de Man, 1880 (s) 

 Lip region set off by constriction; width 2.5% or more 53 



53. Lip region width about two and one-half times its height 



spengelii de Man, 1912 (s) 



Lip region width about three and one-half times its height 

 ...... gaussi Steiner, 1916 (s) 



5U. Head rounded 55 



Head truncate 56 



55. Body strikingly black atratus Linst., 1901 (a) 



Body not black . thermae Hoeppli, 1926 (a & s) 



56. Lips prominent, somewhat angular 5? 



Lips not prominent and angular, 58 



57. Female prerectum twice length of rectum; supplements two spicula 



lengths anterior to anus agilis de Man, 18&0 (s & a) 



Female prerectum as long as rectum; supplements beginning opposite 

 ends of spicula .... proximus Th. & Swang., 1936 (s or a) 



58. Lips conoid; length over U.O mm saprophilus Peters, 1930 (a) 



Lips low and inconspicuous; length under i4.0 mm . 59 



59. Vulvar region with sensillae; supplements spaced 



intervallis Th. & Swang., 1936 (s) 



Vulvar region without sensillae; supplements contiguous 60 



