4 University of Michigan 



Agriogomphus hamatus, new species 



Descripiiun: Abdomen, male 23.5-24 mm.; female 2^-24 

 mm.; hincl wing, male 17.5 mm.; female 19-20 mm. 



Male. — Rear of head pale yellow, dark brown about the 

 foramen ; face and f rons above olive green, labrum with the 

 anterior edge straight, parallel to the base, the free borders 

 margined with yellow, which shades into the green, and a 

 median brown spot ; f rons above with a median basal triangu- 

 lar brown spot, the apex of which may reach the angle of the 

 frons or only half this distance. Vertex and occiput dark 

 olive green or brown ; the surface posterior to the postocellary 

 ridge relatively flat, the occiput occupying a relatively large 

 part of the area ; the occiput rounded off posteriorly, without 

 any ridge or keel, and passing, at either end, into the swollen 

 areas back of the eyes ; these areas are similar to those of 

 species of Cyanogomphus and Ischnogomphus, and, like the 

 rear of the occiput, are sparsely covered with bristle-like hairs. 



Prothorax pale yellow, the free edges of the front and hind 

 lobes paler ; a small median brown spot on the front border ; 

 some obscure markings about the suture between the front 

 and middle lobes; similar in shape to that of the female (PI. 

 I, figs. 7 and 8). 



Thorax greenish yellow, marked with black and brown (PI. 

 I, fig. i) ; above and especially towards the median line the 

 pale color on the mesepisternum is pale dull blue ; in bright 

 colored specimens the black median area and the black upper 

 part of the dark stripe on either side of it stand out con- 

 spicuously in the color pattern ; the pale color of the thorax 

 grows brighter and clearer posteriorly ; beneath the same shade 

 of greenish yellow, but much paler. 



Abdomen with an annulate, and, for a gomphine, intricate 

 color pattern ; sides of i and 2 same color as metepimeron. 



