260 H. A. HAGEN. 



Head cordate, eyes prominent, body hairy; antennae short, stout, third joint 

 less than thrice the leno;th of the two basal ones, flat, ovoid, very little bent in- 

 wards, the apical third about half as broad as long; fourth joint rudimentary, 

 represented by a small tubercle with a faint black dot on tip; mask one-third 

 longer than broad, quadrangular, the basal third narrowed; middle third pro- 

 duced in a short rounded lobe, with pavement teeth and a comb of flat scales; 

 palpus short, straight, somewhat narrowed to the rounded tip, very finely serrate; 

 movable hook reaching scarcely the base of the opposite one, sharp, straight, bent 

 a little on tip; wing cases covering the base of 4th segment, abdomen elongate, 

 about one-third broader than long, little broader than the head, slowly tapering, 

 segments of equal length, 10th shorter; lateral spinee none except a rectangular 

 production of segment 9 ; dorsal hooks on 2 to 9, less developed on segments 4 to 

 6; scars as usual; genital not marked ; appendages twice as long as segment 10, 

 triangular, very sharp, the laterals one-third shorter; legs short, slender, posteriors 

 not exceeding 6th segment; third joint of posterior tarsus longer than the two 

 basals together. 



The place of this species is doubtful, the more as the want of marks 

 of genitals may prove that the nymphae are far from full grown ; never- 

 theless, the principal characters are those of Ophiogomphus, differing by 

 a little longer mask, more straight movable hook, longer more cylindrical 

 abdomen and lack of lateral spines. There is indeed a species from 

 Northern China described 0. spinicornis Selys, said to be nearly related 

 to O. serpentinus. As the nympha of the latter species is still unknown 

 I feel not warranted in supposing that the described nympha may belong 

 to the only known Asiatic species. 



Sub-genus Gomphus (raised). 

 Selys Monogr. Gomphin. p. 115. 



Body flat, broad; third joint of antennae twice the length of the two basals; 

 mask quadrangular, middle third of front border straight, or nearly so; palpus 

 with a strong end hook, dentate before it; abdomen flattened, broader than the 

 head, two to three times longer than broad, segment 9 little longer than 8; 10th 

 shorter; lateral spines on 6 to 9, or 7 to 9 ; dorsal hook very faint on 9, or more 

 developed on 3 to 9, or on 6 to 9; legs with strong hook on tibia; third joint of 

 posterior tarsi as long as the two basal. 



This group is still somewhat polymorphous, as G. milffatissimns has 

 been considered the type with G. (idelphus ? ^ fraternvs .^, exilh minutns ?, 

 furcifer .^, and perhaps amnicola ? and graslinellus ?. To a somewhat 

 different group, perhaps of higher value, belongs G. spinosus ?. Finally, 

 two species from the Amazon and Himalaya are more different. I have , 

 avoided any farther division, as of the fifteen species described only four 

 are raised, and as of the other ones only for few of them can a somewhat 

 risked supposition be made. 



