Notes on the Ephemeridoe. 403 
removed, there can be no doubt of their identity with one 
another. There is a sexual difference in the neuration of 
the Avings in Cloeon dipterum, somewhat similar to that 
which is presented bj Baetis undatus.'] 
Page 131, foot-note No. 2 — consueta. This species 
seems to be dipterous, at least some of the specimens do. 
A female subiraago, however, has hind-wings. I stated I 
was doubtful if all of them should be placed together. 
Page 136. Heptagenia semicolorata. My Baetis semi- 
colorata is not at all your species, and the only one like it 
as to the forceps is your vi. 13 of H. fusca. I have before 
me several males and females from England. Judging 
from the egg-valve of the female (which I do not find 
in your work) it is scarcely a Heptagenia even. The 
figure vi. 9 is entirely different. 
[With all deference to Dr. Hagen, I still consider my 
species and his to be identical. The differences between 
his specimens and my figures are due to his examples 
being dried specimens, and my drawings being made from 
specimens only just dead. Want of space compelled me 
to omit the figure of the last ventral plate but one (" egg- 
valve," Hag.) of the female, which is more deeply excised 
than is usual in Heptagenia. I cannot see much pecu- 
liarity in the nymph as compared with the nymph of 
H. longicauda, venosa or lateralis ; bvit I do not possess 
the nymph of a yellow species such as H. elegants. There- 
fore at present I am disinclined to attach much Aveight to 
the peculiarity of the penultimate ventral plate. In dried 
males the lobes of the penis shrink a good deal, and their 
junction is concealed beneath by the penultimate ventral 
plate. This plate, too, is not then backed up by the fleshy 
cushion of integument which, in my figure taken from a 
a recent example, is seen to intervene between it and the 
penis ; and so the last visible ventral segment in a dried 
specimen exhibits only the two triangular lobes Avhich are 
seen in my figure beyond the semicircular protuberance of 
the belly of the segment. To prevent any chance of a 
mistake, I may say distinctly that Stephens' species is 
identical with Curtis' ; Dr. Hagen has seen Stephens' 
types, and his species is identical Avith Stephens' ; and 
I also ha\^e compared my types Avith Stephens', and find 
them likewise identical.] 
