1863.] 
195 
have larvae with three tails nearly of equal length. Unfortunately the 
middle seta of my unique % P. cupidus imago got lost in the handling, 
and I could only guess at its length. I have no doubt now that the 
length I formerly gave “ about 16 mill,” is much too great. 
According to Dr. Hagen, the synonymy of the N. A. species of 
Potamanthus will stand thus:— 
P. CUPIDUS Say, Walsh = Walker = Walker = 
tessellatus Walker. 
P. NEBULOSUS 'W'aWlqi = odonatus Walsh. 
Palingenia. 
'Note 16, p. 174. I now possess 9 9 of group to which P. vitti- 
(jera belongs and % 9 subimago. The 9 dilfers most remarkably from 
the % in the middle seta being nearly as long as the others, instead of 
being only about i as long. In this respect, therefore, Grroup 5, or my 
subgenus A, agrees with Dr. Hagen’s Grroup 2, but differs from that 
Grroup, lsi(. in the anterior legs % being very short and not much longer 
than those of 9 • "^nd. in the four hind legs being short, ^rd. in the 
9 not remaining in the subimago state. 4:th. in the membrane of the 
wings not being “ always folded up in the dead specimens.”—As re¬ 
gards the 3rd point, I believe that, in certain species, the 9 subimagos 
of which ordinarily moult, they occasionally do not do so^ for I possess 
a 9 subimago of P. hllineata Say, which oviposited in that state. Be¬ 
sides the two 9 imagos of this 5th Grroup described below, I have met 
with two 9 subimaginal integuments which evidently belong here, so 
that there can be no doubt that the 9 subimagos commonly moult. 
The discovery of the very curious fact, that the 9 of this group has 
the 3 setae subequal, will necessitate a revision of the Synoptical Table 
given on p. 368 of my Paper, in which I made an attempt to separate 
our N. A. genera of Ephemerina, without having recourse to sexual 
characters. As revised, the commencement of the Table will read as 
follows 
f First tarsal &c. 
Setse 3, subequal. ' 
First tarsal &e. 
I 
Setse 3, the middle one short 
.....Ephemera. 
Anterior legs 9 ] 
nearly as long > Potamanthus. 
as the body. j 
Anterior legs 'S 9 ] Palingenia subge- 
only 1 as long nus A {=Penta- 
as the body. j genian.g.) 9 only. 
] Palingenia subge- 
. nns, A. {=Pentage- 
j nia n. g.) % only. 
