214 EEV. A. E. EATON ON EECENT EPHEMEEID^ OE MATELIES. 



ano"le of the ventral arcus, is very narrow, and terminates in the hinder lateral angle of 

 the dorsum of the same segment, where it is met by a much broader stripe, which, for 

 a short space, follows the terminal border or joining upwards, and then is suddenly 

 diverted into the next segment, through which it passes obliquely, and subparallel with 

 the lower moiety of the nest stripe, to the terminal border of that segment ; in segments 

 5-7 the borders of the dorsal vessel are perhaps faintly darkened, and there may be a 

 fine indistinct longitudinal streak from the base on each side of it, such as is common in 

 the Ephemeridce ; segment 10 is yellow-ochreous. Venter in the translucent segments 

 pale yellowish horn-colour ; in the opaque segments extremely pale yellowish ochre ; 

 perhaps free from markings, excepting the streaks, already referred to, by the pleurae. 

 Porceps-limbs reddish brown. Setse pitch-, or intense burnt-umber brown. Wings 

 vitreous, almost imperceptibly tinted with bistre-grey ; neuration in opaque view for the 

 most part pitch-black ; the costa, subcosta, and the intervening cross veinlets of the fore 

 wing pitch-, modified with madder-brown ; the finer longitudinal nervures pale near the 

 wing-roots, and the stronger nervures raw-umber brown thereabouts ; in transmitted 

 lio-ht the neuration as a whole becomes pitch-brown. Fore leg in opaque view raw- 

 umber brown ; the femur lighter than the remainder, excepting just at the kuee. Hinder 

 femora, in opaque view, very light raw-umber, with the knee pitch-brown ; tibia? and 

 tarsi darker than the femora and of a yellower tint that approaches brown-ochre. 

 Length of body 11-14 ; wing, d 13-16 ; outer setae (of the larger example) upwards of 

 24 mm. 



Hah. Japan (Von Siebold, Leyden Mus.) ; Yamato, IGth June, and Tokio, 27th Sept. 

 (G. Lewis, M'^^Lach. Mus.). 



SIPHLURUS, Etn. 1868. 



Illusf rations. Adult (details), PL XX. 34c-e [excl. XVIII.? 34 «, & XX. ?34i]; 

 (whole figure) see citation under S. flavidns [_% Baetis], Ed. Pict. (1865). Nijnupli. PL L. ; 

 also poorly represented in P^osel, Insect. Belust. ii. pi. xii. 4-6 (1749), and De Geer, Mem. 

 Sav. Etr. Acad. Paris, ii. 468, pi. xvii. 1 (1755). 



Adult. — In normal species the fore leg of 6 the is usually nearly (y^) as long as the 

 body ; tarsus about 2x\ as long as the tibia, and this \\ as long as the femur ; decreasing 

 gradation of the tarsal joints, — 2 equal to 3 and subequal to 4, 1, 5 ; the first joint | as 

 long as the second. Pore leg of ? f as long as the body ; tarsus very nearly 1| as long 

 as the tibia, and this almost -^ as long as the femur; its joints in diminishing sequence 

 rank 1, 2, 5, 3, 4, and the first is about If as long as the second joint. Hind tarsus of 

 S Ii as long as the tibia, and this about f as long as the femur ; its joints rank 1, 2, 3 

 subequal to 5, 4, and the first is about If as long as the second joint. Ungues all narrow 

 and uncinate. Hind wings well developed, obtusely ovate-trilateral ; dilatation of the 

 marginal area obtu.sely rounded in front; axillar region somewhat ample and well 

 supplied with neuration. In the ? abdomen the relative lengths of segments 2-10 may 

 be formulated thus :— 5, 9, 10, 12, 12, 15, 17, 15, 9; the first is thoracoid. Plem'se in 

 segments 7-9 obtuse behind ; ventral lobe of segment 9 very short, parabolic or obtusely 



