226 REV. A. E. EATON ON RECENT EPHEMERID.E OR MAYFLIES. 



tarsal joint, and all with the extreme tips of the joints of the tarsus and with the ungues 

 hlack ; in transmitted light the ochre changes to dull aniher. 



d . Very similar to the ? , but perhaps rather lighter in colour. Setae pale dull yel- 

 lowish. Forceps pale yellowish brown. Length of body lG-21 ; wing, d 16, 2 19-21; 

 setse, d im. 17 & 5, ? subim. 13 & 7 mm. 



HaO. New Zealand; Christchurch (Wakefield, in M''Lach. Mus. and Brit. Mus.). 



Section 11 of the Genera. — Tyjie of Bcetisca. Adult. — In the fore wing the second 

 axillary nervure (9-) meets the terminal margin close to the anal angle, simulating the 

 usual appearance of the anal nervure and usurping its usual functions : the first axillary 

 (9') and anal (8) nervures simulate complete intercalar nervures of the anal-pobrachial 

 interspace, and are immediately adjacent to each other ; the third and fourth axillary 

 nervures meet the inner margin before the middle, occupying the usual places of the 

 first and second. Pronotum of minimum proportions ; mesonotum excessively developed. 

 Xyniph. — Pal2:)us of maxilla i. shorter than tlie lacinia. Pronotum and the mcsonotal 

 sutures undefined in adolescence, the wings being immersed in a large notal hood or 

 shield, which obtects the tracheal brauchise and a large portion -of the abdomen, 



B.ETISCA, Walsh, 18G2, 



Illustrations. Adult (details), PL XXI. 37 ; (whole figure) subim. see unpublished 

 drawing by Abbot, Brit. Mus. Cat. MSS. 460 c, vol. xii. pi. 42 bis. No. 662 (1792). 

 Nymph, PI. LII. ; see also citations under B. ohesa of Walsh [with circumspection] 

 (1864) and Vayssiere (1882). 



Adult. — Pore leg of 6 little longer than the body [as 8'5 is to 7 or 8] ; tarsus scarcely 



2| as long as the tibia, and this little more than f as long as the femur ; the tarsal 



joints in order of sliortening rank 1, 2, 3, 4, 5, and the first is very nearly If as long as 



the second joint. Fore leg of $ about |- as long as the body : tarsus barely longer than 



the tibia, and this about f as long as the femur ; the tarsal joints in decreasing length 



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



$ about ly as long as the tibia, and this | as long as the femur ; the proportions of the 



tarsal joints approximate to those of the joints of the fore tarsus, but the first is 



scarcely If as long as the second joint. Ungues each unlike the other in every tarsus. 



Hind wdngs ample, subrotund ; dilatation of the marginal area obtusely rounded off in 



front; axillar region of moderate dimensions, but with plentiful neuration ; intercalar 



neuration unusually long and plentiful ; cross veinlets remote from the terminal margin. 



In both wings cross veinlets are very numerous, and many of them are delicate ; in the 



fore wing they are not restricted from the vicinage of the terminal margin, where many 



of the longitudinal nervures are provided with short branchlets. Prosternal projection 



bifid ; mcsothorax remarkably stout ; abdomen relatively short. In the ? abdomen the 



proportional lengths of the 3rd-10th segments may be formulated thus : — 6, 6, 7, 14, 7, 



7, 7, 6 ; of the remaining two segments, the first is thoracoid, and the second was not 



sufficiently traceable for measurement in the dried specimen examined ; the pleurae of 



segments 7 and 8 are obtuse, those of segment 9 acutely truncate behind ; the ventral 



