on the Ephemeride. 41 
Family HPHEMERIDAi. 
(ArxipTerA, Brullé; Anisoprera, Stephens). 
The Ephemeride are hexapod insects which have many- 
jointed caudal setee; which carry their fore-wings erect 
and unfolded; and which in the imago have abortive 
mouth organs. 
Antenne aristate; the basal two joints the largest, the 
bristle many-jointed. Ocelli three. Oculi compound or 
complex. Legs slender, the anterior pair the longest; 
tarsi distinctly jomted, terminated by claws. Anter- 
ior wings large, creased lengthwise, but never folded 
together ; costa united by a stout cross-veimlet to the 
radius near the base of the wing; subcosta uninterrupted 
at the nodus. Posterior wings sometimes absent, some- 
times rudimentary, at the utmost small. Abdomen ten- 
jomted: the first abdominal segment joimed immoveably 
to the metathorax ; the ninth provided in the male with 
a pair of abdominal legs in the form of claspers (forceps) ; 
the tenth bearing (two at the fewest, three at the most) 
multiarticulate caudal sete, which are used as balancers ; 
the alimentary canal straight, apparently destitute of 
salivary glands, and inflated with gas; many short ex- 
cretory tubules are appended to the large intestine ; the 
penis is situate at the apex of the ninth segment, and 
is either hidden or exposed ; the oviducts terminate in 
the joining of the eighth and seventh segments, 
In coition, the male flies under the female and seizes 
her prothorax with his elongate anterior legs, simulta- 
_ neously bending the tip of his abdomen upwards and 
forwards, and clasping the proper segment of her body 
with his forceps. During their connexion, which is of 
brief duration, the pair are chiefly supported by the female, 
and they gradually descend slowly in the air, sometimes 
even to the ground. When they separate, the male 
rejoins his companions. The female retires to the water, 
and deposits the eggs impregnated, settling again and 
again upon the surface of the water with extended setzx, 
until the extruded eggs become detached from the rest. 
This done, she, in some genera, returns to the general 
assembly, and “pairs again, and then again deposits 
eggs ; and so on, until all the eggs are disposed of: thus 
the same female may be served by several males; and like- 
wise the same male may frequently serve several females, 
