CAMPSURUS.— CHOROTERPES, 5 
Hab. GUATEMALA (one ¢ imago, in Mus. de Selys-Longchamps) 1 ?. 
Both the figures quoted are derived from the same original drawing. 
HEXAGENTA. 
Hexagenia, Walsh, Proc. Ent. Soc. Phil. ii. p. 197 (1863). 
This genus is chiefly known from the New World, where it extends at least from 
Canada to Buenos Ayres. There is, however, in Mr. McLachlan’s collection, a specimen 
from N.W. India; cf. Eaton, Rev. Mon. Ephem. t. 7, fig. 11 @ (1883) (undescribed). 
Some of the American species have a very extended range. 
1. Hexagenia mexicana. (Tab. I. fig. 4, 3.) 
Hexagenia mexicana, Eaton, Rev. Mon. Ephem. p. 50 (1883). 
Hab. Mexico (Sallé*; one ¢ imago in Mus. Hagen), Atoyac in Vera Cruz (Schur 
mann; one ¢ imago). 
The latter specimen enables the published description to be supplemented as 
follows :— 
Dorsum of abdomen pitch-black, with a single longitudinal series of translucent triangular subochreous spots 
on each side of the median tract, extending from the second to the ninth segment. These spots, situated 
very near the bases of the segments, are isolated by a considerable breadth of the dark ground-colour, 
which tends to invade their lower angles ; those towards the commencement of the series have their upper 
anterior angle right-angled, but the corresponding angles of the hinder spots become more obtuse. Venter 
light burnt-umber, or warm sepia-brown ; the ninth segment darker, except in the median tract; on each 
side of the anterior segments a dark streak runs backwards from the basal angle. Forceps to the begin- 
ning of the second joint of the limbs almost concolorous with the ninth segment, and then pitch-black to 
the tips. Setz piceous. In this specimen the only portions of the hinder legs that are distinctly pitch- 
brown are the terminal joint and the ungues; elsewhere the traces of this colour are very faint. 
Length of wing 16, body 19 millim. 
Many of the Mayflies of the Leptophlebia-type in Messrs. Godman and Salvin’s 
collection probably represent new genera. But until both sexes of the flies and their 
nymphs are known, it will be best, perhaps, to place them provisionally in the named 
genera to which they are most nearly related, and to state the points wherein they 
appear to depart from the normal standards of those genera. This is said with 
particular reference to species here referred to Thraulus and the following genus. 
CHOROTERPES. 
Choroterpes, Eaton, Ent. Monthly Mag. xvi. p. 194 (1881); Rev. Mon. Ephem. p. 104, t. 12. 
fig. 19 (adult details), and t. 34 (nymph) (1884). 
Besides a single European species, and one (tn Mus. McLachlan) from Tenasserim 
Valley, which is normal, the genus includes the two following. 
