ODONATA OF BAJA CALIFORNIA. 47I 



aud mediau sectors curved at its middle away from the former or its 

 posterior branch, with 3-7 rows of cells between them at that place. 

 Subnodal sector forked or with several small branches. Suture between 

 the eyes not longer than combined length of vertex and frons measured 

 on mid-dorsal line. Subcosta not prolonged beyond the nodus. S with 

 aual triangle and anal angle on hind wings, and auricles on 2. 



JiJschna. 



II. Upper piece of arculus shorter than the lower piece, its upper sector 

 arising close to the median vein (midway between the latter and the 

 lower sector). External branch of lower sector in hind wings approach- 

 ing the upper sector for its apical half, being parallel to it and separated 

 by one row of cells. 4 ( 3 ) or 5 ( $ )-10 usually with a supplementary 

 lateral carina above the usual one. S with no anal triangle on hind 

 wings, anal angle rounded off, no auricles on 2. Anax. 



Subfamily Libellulin^;. 



I. Lower angle of triangle of front wings placed as far beyond the level 

 of the outer angle of the triangle of the hind wings, as the latter triangle 

 is long; eyes connected for a space at most not much greater than the 

 thickness of the vertex; no antenodel concavity on front margin of 

 wings; tarsal nails toothed. 



Ab. seg. 3 and 4 with two additional transverse carina?, 5 with one; 

 nodal sector waved; anterior lamina oiS bifid. Pantala. 



Ab. seg. 3 and 4 with one additional transverse oarina, 5 with none; 

 sectors of arculus arising from a common stalk; triangle of front 

 wings crossed; nodal sector not waved or broken; anterior lamina 

 of 5 entire. Tramca. 



II. Lower angle of triangle of front wings placed on a level with the 

 outer angle of the triangle of the hind wings or only a little beyond it; 

 otherwise as in (I). 



A. Hind lobe of the prothorax with its middle portion produced 

 upwards and backwards and narrower than the other lobes, its hind 

 margin usually entire; triangle not densely reticulated. 



a. Sectors of the arculus in the front wings not arising by a 

 common stalk. 



Nodal sector waved in its middle, supratriangulars ^jresent 

 on front wings, triangle of hind wings often crossed, i with 

 no ventral hooks on 1st ab. seg., $ with no projecting 

 vulvar lamina. L'lhellula. 



b. Sectors of the arculus in the front wings variable with or 

 without a common stalk at origin. 



Nodal sector waved in its middle, triangle of hind wings 

 cross veined, 6 with no ventral hooks on 1st ab. seg., $ with 

 vulvar lamina projecting at right angles to the abdomen. 



Pseudohon. 



