[February, 
190 
uncinate. Proximal joint of £ forceps’ limb sub-equal in length to 
the rest put together. Nymph latent, with seven pairs of abdominal 
tracheal branchiae, all nearly alike in form ; each one bifid into unequal 
segments, which are divided into slender filaments. Type, H.fusca 
(in Ephemera), Curt. S yn., Leptophlehia, ser. 5, with L. Picteti, Etn., 
1871 ; also misprinted II ale cop hlehia (Etn., MS.), by llostock, 1880. 
Distrib., Temperate and Southern Europe. [N.B. — The citation here 
given of L. Picteti is based upon recollection only.] 
As I have suggested (in private correspondence) the possibility 
of Dr. Joly’s Ccenis maxima nymph being the young of a Tricorythus , 
1 take the opportunity of stating that (judging from specimens in a 
better condition of preservation than those upon which 1 relied in the 
first instance), it is, after all, more likely to be a real Ccenis. The 
examples previously examined by me, w r ere all of them defective. 
CALLIBiETIS, n. g. 
Allied to Baetis. Tw r o long caudal setse, in $ two and a half 
times, in $ twice as long as the body. Fore-wing with several cross- 
veinlets in the marginal area before the nodus, in both sexes, and with 
single (if any) interneural veinlets at the terminal margin. Hind- 
wing tri-nervate, with several cross-veinlets, and with the costal 
shoulder very obtusely rounded off (compare Trans. Ent. Soc. London, 
1871, pi. v, 27 — 29). Fore tibine in £ about one and one-sixth, in $ 
three-quarters, as long as the femur ; the tarsus in $ about as long 
as, in $ about two-thirds as long as, the tibia, the 3rd joint in £ shorter 
than the 2nd joint. Type, C. pictus (in Baetis formerly), Etn. 
Distrib., North and Central America and Australia. 
Baetis, Leach (restricted). 
Two long caudal setae, in two to two and a half, in $ one and 
one-fourth to tw r o and a half, times as long as the body. Fore-wing 
without cross-veinlets in the marginal area before the nodus (as a rule, 
almost without an exception) in both sexes, and with interneural 
veinlets in pairs at the terminal margin. Hind-wing bi-, or tri-nervate 
(the intermediate nervure in the latter case sometimes forked), and, 
generally speaking, destitute of cross-veinlets ; usually oblong-ovate, 
with an acute costal projection, seldom ( B . atrehatinus) without any 
costal shoulder at all (compare Trans. Ent. Soc. London, 1871, pi. v, 
16 a to 26 a). Fore tibia in $ about one and one-third times as long, 
in $ the same length as the femur ; fore tarsus in ^ about one and a 
