1863.] 
241 
basal spot is partially confluent, The superior S abdominal ap¬ 
pendages are as I have described them in vastus Hagen, but the change 
in their curvature takes place at f (not |) of the way to their tips, and 
instead of the “ inferior small spine” at the change of curvature there 
is an inferior small blunt tooth; the inferior % appendages differ from 
those of vastus in being only | (not |) as long as the superiors, and in 
gradually curving inwards and upwards for their whole length, their 
tip obtuse and with a very small terminal thorn directed upwards. In 
vastus^ on the contrary, the tip itself “curves suddenly upwards at f 
their length,” and terminates acutely in a robust cone when viewed in 
profile, obtusely when viewed from above; whereas I erroneously de¬ 
scribed these appendages as “ obtuse.” lO^A. There is always a “ pos¬ 
terior” yellow vitta, slightly abbreviated at base, on the anterior femur 
S 9 i 0^ Ihe posterior femur 9 , but never in % , there is an “ an¬ 
terior,” unabbreviated, yellow vitta, as in M. Selys 9 • The knees are 
generally spotted with yellow above, and generally on the tibiae there 
is a slender “ superior” basal vitta, which is sometimes subobsolete, 
and occasionally obsolete. This last vitta is described by Say. 11?A. 
The wings are not even “slightly yellowish” at base; the costal vein 
is almost always conspicuously yellow on the outside; the pterostigma 
varies from bistre-brown to pale-reddish-brown or fawn-color, and sur¬ 
mounts 3—4J cells. Antecubitals (front wings) 12—14. Postcubi- 
tals 9—12; two discoidal areolets, commencing always with 3 in both 
wings and in one wing of one % with 4. 12th. Instead of the occiput 
being “ more elevated at the sides in 9 than in % ,” I see no difference. 
The middle of the % occiput, however, rises much higher above the 
line of the eyes than the middle of the 9 occiput, which scarcely rises 
at all above the line of the eyes. The abdominal appendages in my 
unique 9 are yellow, not “ black,” except at the extreme base and tip. 
Length % 53—56 mill. 9 54 mill. Expanse % 61—67 mill. 9 68 
mill. Abd. % 35i—39 mill. 9 38 mill. App. sup. % 1^ mill. Hind 
femur % 9—9^ mill. 9 10 mill. Front wing % 31i—33 mill. 9 34 mill. 
Hind wing % 29^—31 mill. 9 32^ mill. Pterost. inf. % 3 mill. 9 3i 
mill. Seven % , one 9 • Occurs in June both on the Mississippi 
and on Rock River. The difference in the coloration of the % 9 
posterior femora is very remarkable and unusual, and re-occurs in G. 
yraslinellus Walsh, (see below.) In the Synopsis of K. A. Neur. (p. 
