276 EEV. A. E. EATON 02s EECENT EPHEMEEID.E OK MAYFLIES. 



teg Tpale straw- or amber-yellow ; the troehauter, a baud in the middle aud another at 

 the tip of the femur, the base of the tibia, and the extreme edges of the tarsal joinings 

 pitch-black; the other legs wanting. "Wings vitreous; longitudinal neuration pellucid, 

 -excepting that the costa, subcosta, and radius are piceous towards the tip of the fore 

 wing ; cross veinlets jiiceous, and narrowly bordered with piceous. 



2 . Very similar; but the general colouring of the body is brown-ochre instead of 

 yellow-ochre. In the hind wing there are rather more cross veinlets than in the other 

 sex. Length of body 6 ; wing, d 7, ? 8 mm. 



Sab. Lahat (in Leydeu Mus.) ; received from Mr. C. Hitsema. 



ECDYURUS, Etn. 18G8; revived 1881. 



Illustrations. Adult (details). Pis. XXIII. & XXIV. 46, see also [anatom.] citations 

 of Palmen (1884) under U. angustipenu'ts and venosus ; (whole figures) see citations of 

 Pictet (18i3-5) under U. helvetlcus, purjinrascens, angustipeiinis, obscurus, lateralis, & 

 moiitaniis, and of Curtis (1834) under venosus. Nynqjh, Pis. LXI. [junior] & LXII. 

 (senior) ; see also Pictet, o/j. cit. (1843-5) pi. 10. 



Adult. — In the hind tarsus joints 1-4 usually diminish successively in length, but 

 the first is sometimes equal or subequal in length to the second joint ; in the inter- 

 mediate tarsus the first joint is moi'C commonly as long as the second joint ; first joint 

 of the 6 fore tarsus usually about h as long as the second (in E. helveticus scarcely ^ as 

 long as the second joint), which is nearly of the same lengtli as the third joint ; first 

 joint of the ? fore tarsus shorter tliau the second, which exceeds the third joint in 

 length. Penis-lobes stout, usually broadly trilateral, but sometimes obovate ; stimuli 

 well developed, adjacent to the median line. Fore leg of 6 l-lj as long as the body; 

 tarsus about twice as long as the tibia, which is almost as long as the femur; tlie tai'sal 

 joints in the order of their shortening usually rank 2, 3, 4, 1, 5 [in E. heloeticus 2, 3, 4, 

 5, 1] and the first is usually about ^ [in E. heloeticus about ^ or j] as long as the second 

 joint. Fore leg of $ subequal in length to the body or about f as long as it ; tarsus 

 ^-\\ as long as the tibia, which is about f as long as the femur ; tJie tarsal joints in 

 the order of their shortening rank usually 2, 5, 3, 1, 4 [in E. helveticus 2, 5, 3, 1 equal 

 to 4] and the first varies in proportion to the second joint from about f— n: as long. 

 Hind tarsus of <s about y as long as the tibia, wliicli is about Ij as long as the femur; 

 the joints in the order of their shortening usually rank 5, 1 equal to 2, 3, 4, but in the 

 $ tarsus and in that of E. helveticus <s they rank 5, 1, 2, 3, 4. Ungues each unlike 

 the other in every tarsus. Hind wings of the usual form ; the axilhu' region narrow. 

 In the dried ? abdomen the relative lengths of the dorsal segments 2-10 may be 

 formulated thus : — 5, 8, 9, 9, 9, 9, 7, G, 6 ; ventral lobe of the ninth segment entire. 

 Forceps-basis of s usually slightly or moderately curved saliently behind betw^een the 

 insertions of the limbs, and sometimes with a small blunt projection or tooth on each 

 side of the curve adjacent to their insertions. Penis-lobes stout, usually expanded 

 broadly outwards at the tips, but sometimes obovate ; stimuli well developed, adjacent 

 to the median line. Caudal seta? of 6 2A-3 times the length of the body, those of 2 



