EEV. A. E. EATON ON RECENT EPHEMEEID.E OR MAYFLIES. 233 



tibia, and this about f as long as the femur ; the tarsal joints in order of shortening rank 

 1, 2, 3, 5, 1 — the first is about IJ as long as the second joint, and not quite ^ as long as 

 the tibia ; ungues each unlike the other. In the anal-axillar interspace of the fore wing 

 the two iutercalar nervures nearest to the anal (8) nervure are shorter than the next two. 

 Hind wing well developed [defective in the illustrations] ; the dilatation of the marginal 

 area angular in front. Eorceps-basis transverse, with a small subobtuse projection on 

 each side of its distal margin in proximity to the insertions of the limbs. Eorceps- 

 limbs 3-jointed, with the terminal joint minute. Median seta aborted ; the outer setse 

 defective in the specimens examined. ? unknow^n. 



Type. Th. detenniiiatus (in XBaetis), Walker. 



Distribution. Java and the Philippines. 



Etymology. OaXepoc. and acpvpov, from the size of the ankle or proximal joint of the tarsus. 



Thalerosphyrus determinattis. Walker. Plate XXII. 40 (wings, legs [part], forceps). 



XBaetis determinata, ! Walk., List, of Neuropt. lus. iu Brit. Miis. part iii. 567 (1853). 

 Heptagenia determinata, !Etn., Trans. Ent. Soc. London (1871), 157. 

 Thaler osphyrus [type] determinattis, ! Etu., Ent. Mo. Mag. sviii. 22 (1881). 



Imago {dried), S . — •Piceous with a yellowish stripe down the back, including (Jide 

 Walker) some piceous marks in the abdominal segments. Setae in 2 intense warm sepia- 

 brown. Legs flavescent, the femora broadly banded in the middle and distally with 

 fuscous ; both extremities of the tibiae, and the tarsi also fuscous. Wings vitreous, with 

 the neuratiou mostly fuscous ; the costa of the fore wing towards the base bright 

 yellow-ochreous, but in the marginal and submarginal areas somewhat thickened and 

 pitch-brown. Length of body, <5 (shrunken) 11 ; wing 12 ; setse, ? im. 27 mm. 



Mab. Java (Brit. Mus. and Leyden Mus.). 



Thai.erosphyrus torribus. Walker. 



XBaetis torrida, ! Walk. List of Neuropt. Ins. in. Brit. Mus. part iii. 571 (1853). 

 Heptagenia torrida, ! Etu., Trans. Ent. Soc. London (1871), 157. 



Imago (dried), $ . — Thorax dark rufo-piceous above. Abdomen discoloured, dark at 

 the hinder borders of tlie segments. Setse lost. Eore legs very dark rufo-piceous, darker 

 than tlie notum ; hinder legs with femur and tiliia translucent light raw-sienna brown, 

 and witli tarsus and the tip of the femur light pitch-brown or rufo-piceous. Wings of a 

 light raw-umbre grey tint, the marginal and submarginal areas of the fore wings darker ; 

 neuration pitch-brown. Length of body (shrunken) S, wing 9 5 mm. 



Sab. The Philij)pine Islands. 



Section 14 of the Genera. — Type of Ecdyurns. Adult. — Wiug-neuration conformable 

 in plan to that predominant in Section 13 of the genera, described at p. 230. Hinder 

 tarsi obviously shorter than tlie tibia. Nymph. — Palpus of maxilla i. longer than the 

 lacinia. Terminal margins of the fore wings free. Pronotum distinct. 



The hind wings of the adult flies are well developed, as a rule, and have the costa 

 iharply elbowed at about the first |th of the wing's length ; the marginal area, moderately 



