368 



PROCEEDINGS OP THE ACADEMY OP 



f Eyes J contiguous, 



simple. (Wings 4, ("Three long and equal setae, 

 hind wings wide,*! Three seta?, the middle one 

 with numerous (_ rudimental. 

 veins.) 



Cross-veins less nume- 

 rous ; costal cross- 

 veins, except the ba- 

 sal cross-vein and on 

 the terminal | of cos- 

 ta, almost invisible 



and partially absent.^' Eyes cf contiguous, j ther numerous (50 or CO.) j 

 (Many short terminal 

 isolated veinleta at 

 the tips either cf the 

 front or hind wings, 

 except in Ca-nis.) 



EP3EMERELLA, D 

 > BiETISCA, n. g. 



( Wings 4, cross-veins ra- \ Cloe, subgenus A. 



double (Wings 4 i Wings 4,eross-veins sparse 1 c sull 8 B . 

 or 2; hind wings] (1418.) 



with 2 or 3 veins.) Wings 2 cross-veins sparse 1 c sub g el ,us C. 

 V (14 18.) 

 Eyes cf remote, sim-") 



pie. (Wings 2, se- >- Cknis. 



tse 3.) 



} 



As it is often difficult in the dried specimen to distinguish whether the tf 

 eyes are single or double, and as sexual generic characters are practically in- 

 convenient, the following synoptical table, which excludes them, except in two 

 subgenera, has been prepared : 



First tarsal joint entirely") 

 obsolete in $ ? 4 hind \- Ephemera. 

 legs. 

 ' Setae 3, subequal. I First tarsal joint indis- 



Costal cross-veins nu- 

 merous, robust, regu- 

 lar ; wings 4. 



A 



:L~'s d , c TS'! sa f po.. 



Setae 3, the middle 

 one rudimental. 



B/ETis, subgenus A. 



the tibia in cf 9 4 hind , 

 legs, but not obsolete. j 



Sets 3, the middle) .p A LiNGENiA,subgenus A. 



one short.) j 



f First tarsal joint shorter! p subgenus B. 



than second. I 



First tarsal joint longer] 

 than second, except in ' 

 anterior cf tarsus, where j 

 they are equal. J 



First tarsal joint longer^ 

 than second in all cf ? H 

 t legs, 

 f First tarsal joint shorter] 



!than second, indistinct 1 , 

 and connate with the ti- j 

 bia in all cf 9 legs. J 



| First tarsal joint shorter! 



I than second, distinct and > Palingenia, subgenus C. 

 { free in all cf ? legs. J 



("Three equal setae. Efhemerella, n. g. 



f Wings 4, hind wings J Three aeta!i midc n e one ru- ) 



Costal cross-veins, ex- wltie - (. dimental. S aJEIlsCA ' n - B- 



cept at tip and ex- . ,. , . ( Cross-veins rather nume-ip ,u_- 



treme base, very slen- J Wm ??i' h,nd w,n S 8 ^ roui, (50-60.) 



i all cf ? SBiETis, subgenus B. 



M 



Bjbhs, subgenus C. 



der ; entirely absent 

 on some part of the 



costa. 



' > Cloe, subgenus 



[Wings 2. 



(Cross-veins sparse, (14-18) Cloe, subgenus B. 

 f Two setae ; cross-veins 1 . 

 J sparse, (14 18.) )' 



1 Three setae ; cross-veins 1 r 

 I very sparse, (46 ) j^^s. 



Cloe, subgenus C. 



B/ET1S. 



\\ Bastis. Subgenus A. First tarsal joint distinct, large, always larger than 

 any of the three following, except in the anterior $ tarsus ; joints Irregular- 

 ly and notably diminishing in length, except in the anterior <$> tarsus, where 

 joints 1-4 are long and subequal and joint 1 is distinctly free. A rndimental 

 intermediate seta, distinctly articulate, sometimes turned downwards. 



BjEtis femobata, Say. Undescribed imago. $ Piceous. Eyes in the liv- 

 ing insect pearly whitish on their superior , with a moveable black spot ; the 

 inferior \ pale dusky, divided from the whitish part by a definite line ; antennas 

 dusky, pale at extreme tip. Prosternum a little marked with whitish, some- 

 times almost entirely whitish ; a broad transverse oblong whitish band between 

 the hind coxae, sometimes very conspicuous. Abdomen with joiuts 1-5 whitish 

 hyaliDe, each with a narrow piceous band before the incisures, an obscure, ob- 

 long, medial spot on each side of the dorsum, and a slight piceous pulverules- 



[Sept. 



