138 NEOTROPICAL PSELAPHIDAE 



median depression on ventral face, or strongly swollen at apex 



Group XLVII. 



9. Antennal segment X abnormally large in both sexes, being as wide or 

 distinctly wider than the eleventh segment which is also very large. 



(PI. XVII, 10) Group XXXV. 



Antennae with the tenth and eleventh segments normal, but one or 

 more of the intermediate segments (fourth to ninth) abnormal 10 



10. Antennal segment V abnormally large, distinctly larger than the fourth 



or sixth segments, the sixth segment not abnormal. (PI. XVII, 



11-15) Group XL. 



Antennal segments V and VI simple in the females and very abnormal 

 in the males (PI. XVII, 16) Group XLI. 



11. Antennae with segments normal in both sexes 12 



Antennae with" one or more segments abnormal in the males, and 



normal in the females 13 



12. Head with the anterior, median fovea present and incising the frontal 



margin so that it is abnormal in position Group LI. 



Head with the anterior, median fovea wholly absent .... Group LIV. 



13. Antennal segment V of the male (female unknown) slightly longer 



than either fourth or sixth segments ; anterior, median fovea of head 

 present between antennal bases, but minute; middle tibiae armed 

 with a small spine near apex; posterior femora strongly dilated, with 

 the dilation broadly and entirely excavated on the posterior face; 



known only from Peru Group LXIV, new group. 



Anterior, median fovea of the head wholly absent, or if present ab- 

 normal in position or subequal in size to the two foveae between the 

 eyes, not minute as described above; legs in the male not so formed 14 



14. Head with the vertex either (1) medianly swollen or vaulted between 



the two inter-ocular foveae, or (2) medianly and longitudinally 



carinate between the inter-ocular foveae 15 



Head with the vertex normally convex to flattened between the inter- 

 ocular foveae 16 



15. Head with the vertex simply but prominently swollen between the 



two vertexal foveae in both sexes, this swelling does extend towards 

 the front, but does not reach the frontal margin ; males with meta- 

 sternum distinctly, medianly impressed and females with meta- 



stemum flattened Group LIX. 



Head with the vertex sharply, medianly, longitudinally carinated be- 

 tween the inter-ocular foveae, this carina especially well formed 

 posteriorly to occipital crest (male), or vertex with the carina not 

 sharp, but in the form of an obtuse elevation between the inter- 

 ocular foveae Group LV (in part). 



16. Anterior median fovea of the head present but abnormally placed, 



either incising the frontal margin, or wholly on the declivous front 17 



