56 EEV. A. E. EATON ON EECENT EPHEMEEID^ OE MAYFLIES. 



in certain positions, wliile the subcosta, radius, and prfebracliial nervures of the fore wing 

 remain yellowish, other finer longitudinal nervures appear greyish (Galena). 



Imago, <s (liviiifj). — Eyes bright greenish yellow above, black below {Walsh). — {Dried.) 

 Pronotum translucent, sometimes tinged with bistre-grey overlying yellow-ochre, tra- 

 versed lengthwise on each side by a lighl burnt-umber or pitch-brown streak reaching 

 from the occiput to the fore-wing roots. Meso- and metanotum of a colour inter- 

 mediate between light brown-ochre and Mars-yellow, varied posteriorly with the former 

 colour. Abdomen varying from light yellowish-ochre, or light raw-sienna, to light 

 brown-ochre, marked on the dorsum with dark madder-brown, and on the venter with 

 intense burnt-umber, the form and extent of the markings presenting much variation. 

 In strongly marked specimens the dorsal pattern consists of a median stripe the whole 

 length of the back, with a jagged stripe on each side of it : the median stripe may 

 maintain a nearly even width in every segment ; sometimes in segments 1 and 2 the 

 whole of the dorsum (excepting at the joinings) is dark, in segments 3-6 (whose 

 joinings are also pale) the median stripe is narrowed in every segment from behind 

 forwards so as to be resolved into a series of triangular blotches, while in segments 7-9 

 its breadth is more equal, and it terminates in a spot at the base of segment 10 ; but 

 in ill-marked specimens both median triangles and stripe ai'e either deficient, or 

 reduced to a linear streak along the dorsal vessel in segments 7-10. The lateral stripes 

 of the dorsum in strongly-marked specimens are each composed of a series of diagonal 

 triangles or of diagonal stripes extended forwards from the hinder borders, nearly in the 

 middle, to the anterior angles of the segments, which stripes in segments 7-9 are some- 

 times confluent posteriorly with the median stripe ; in some specimens the triangles, 

 instead of tapering forwards, are reversed ; in ill-marked specimens the stripes are almost 

 linear. Pectus and ganglionic track intense burnt-umber, the latter sometimes Ul- 

 defined ; in segments 2-9 at each anterior lateral angle is a small triangular spot of the 

 same colour. Setae light Boman-sepia brown, many of their joints becoming whitish 

 yellow-ochreous anteriorly in varying extent; sometimes the lighter colour is pre- 

 dominant, and, in the midst of the seta, only every fourth joint and more or less narrow 

 annulations at the distal extremities of the other joints remain of the darker colour. 

 Pore leg as an opaque object madder-brown from the trochanter to the end of the tibia, 

 but slightly blackened at the extreme distal border of the femur and at the base of the 

 tibia ; tarsus ligliter ; the terminal and proximal joints of the tarsus, the tips of its inter- 

 mediate joints, the ungues, and the distal extremity of the tibia, blackish, or intense 

 burnt-umber ; viewed with transmitted light the femur and tibia appear fuscescent. 

 Hinder legs as opaque objects very light brown-ochreous, but as transparencies light 

 amber-yellow ; the ungues, terminal joint, and the tips of the other joints of the tarsus 

 intense burnt-umber brown. Wings transparent, the fore wings very slightly tinted, 

 the hind wings tinted, sometimes as slightly, sometimes more strongly, with light 

 greenish yellow ; the marginal and submarginal areas of the fore wing exterior to the 

 great cross vein, and the longitudinal neuration raw-umber brown, the colouring some- 

 times receding from the costa towards the subcosta ; cross veinlets of the fore wing black, 

 and those in the basal two thirds of the wing between the costa and pobrachial ncrvure (7) 



