EEV. A. E. EATON ON RECENT EPHEMEEID.E OR MAYFLIES. 213 



One specimen, perhaps a dwarf of tlie same species, measures : — length of body, d im. 

 8, wing 10 mm. 



Sab. North America ; larger examples Washington Territory ; smaller example Mt. 

 Hood (M'Lach. Mus.). 



DIPTEROMIMUS, M-'Lacli. 1875. 



Illustrations, Adult (details), Pis. XX. 35 [N.B. — The hind wing is defective] & 

 LXIV. 25. 



Adult. — Fore leg of d about ly as long as the body; tarsus twice as long as the tibia, 

 and this about f as long as the femur ; decreasing sequence of tarsal joints, 1 equal to 2, 

 3, 4, 5. Hind tarsus about f as long as the tibia, which is j^- as long as the femur ; its 

 joints rank 1, 2, 5 subequal to 3, 4, and the first joint is about 1^ as long as the second. 

 Ungues all narrow and uncinate. Pore wing unusually narrow and long in its proportions, 

 rapidly narrowed to the roots in its proximal J, and elliptical beyond that. Hind 

 wings very rudimentary, trilateral and elongate, with the marginal area obtusely rounded 

 off in front. $ unknown. Forceps-basis shallowly, widely, and angularly excised ; 

 forceps-limbs 4-jointed, the basal joint very short resembling a gibbous enlargement of 

 the second, which is longer than the remainder, curved, and bordered on its inner side 

 with a narrow membranous expansion. Penis-lobes narrow, unarmed. Median caudal 

 seta aborted in two specimens, but present in another and then (so far as as can be 

 inferred from the remnant preserved) at least half as long as the outer setss ; these are 

 minutely pubescent, and are upwards of twice as long as the body. Oculi of d obso- 

 letely ascalaphoid, probably contiguous above during life ; anterior ocellus rather smaller 

 than the others. 



Nymph unknown. 



Type. D. tipuliformis, M'^Lach. 



Distribution. Japan. 



Mymology. Sic, nTep^v, and /i?;iioc, from its similarity in aspect to a Tipula. 



DiPTEROMiMUS TIPULIFORMIS, M'Lach. Plates XX. 35 (wings, legs, and genitalia d ,) 

 & LXIV. 25 (hind wing refigiu'ed). 



Dipteromimus tipuliformis,\ M°Lach., Traus. Ent. Soc. London (1875), 170. 



Imago {dried), d . — Pronotum, hinder parts of the mesonotum, metanotum, and the 

 thickened hind border of the first abdominal segment yellow ochreous ; the anterior 

 parts of the mesonotum either raw-umber or pale reddish brown. Abdomen in segments 

 1-6 translucent, the dorsum bistre- or light greenish grey, passing into brownish ochre 

 posteriorly in segments 6-9, and marked on each side in segments 2-7 with angulated 

 piceous stripes ; the foremost stripe lies wholly on the dorsum in segments 1 and 2, the 

 portion in the first segment meeting that in the second segment a little above the 

 hinder lateral angle of the former segment at a very obtuse angle ; the other stripes lie 

 partly along the jileura in one segment and partly in the dorsum of the next segment, 

 in this manner : — the portion in the anterior segment commences at the anterior lateral 



