274 H. A. HAGEN. 



Hogenins with its very flat and large circular abdomen, with the un- 

 usual large, flat, circular third joint of antennae and the very long legs 

 can scarcely be united with the other ones ; the prothorax-stigma is free. 



Finally, the two abnormal nymphge from Kentucky and Japan are out 

 of question till the imago is known. 



In fossil layers the insects of the sub-family Gomphina belong to the 

 oldest Odonata ; among them the Legio Gomphina is the last to appear. 

 Probably what we know now of the Legio Gomphoides, represents only 

 isolated remnants of genera in former times largely developed. Ihe 

 links are lost, or not yet known. 



Genus Progomphus (supposed). 

 Selys Monogr. Gomphin. p. 194. 



The nymphas of Progomphus diff'er by some striking characters from 

 all other belonging to the Legio Gomphoides. The head is large, flat, 

 square, as large as the bulky thorax and the abdomen ; the fourth joint 

 of antennae is about one-fourth as long as the third ; the small but more 

 elongated mask is produced on the front border in a rounded large lobe ; 

 the flat scales of the comb somewhat distant from each other ; abdomen 

 tapering slowly from the base, less rounded above, with dorsal hooks on 

 segments 1 to 9 ; lateral spines from 5 to 9, or 3 to 9 ; last segment 

 conical, free ; appendages sharp, the laterals very short ; abdomen below 

 flat, the two longitudinal sutures ending on each side on the apical angle 

 of segment 8th (instead of 9th, as in all other species) ; the middle legs 

 nearer together at base than the forelegs ; the legs are very strong bur- 

 rowing legs, short and thick ; the tarsi knife shaped. The position of 

 the middle legs and the ventral sutures are alone sufficient to separate the 

 nymphae from all related ones, especially from Onychogomphus. '1 he 

 covered stigma of the prothorax is similar to Gomphus and separates 

 Progomphus from the other genera of the Legio Gomphoides. 



30. Progoiiiphu!^ obscuruN (supposition). 



Selys Monogr. Gomphin. p. 201 ; Cabot, p. 6^ pi. ii, fig. 3. 



Three nymphae in alcohol, male and female, probably full grown, from 

 Wareham, Mass.. May, 18 1)3, by Prof. L. Agassiz ; one in alcohol from 

 Little Wabash River, Effingham, 111., June, 1878, Prof S. A. Forbes. 

 Length 27 to 30 mm. ; breadth (J mm. 



Stout, hairy, Aeschna like: head large, as broad as abdomen, flat, cordate, 

 notched behind, angles globular: antennae stout, third joint very hairy, long, 

 dilated, more than twice the length of the two very short basal, fourth joint short, 



