1897.] : Entomology. 167 
exit of the larvae these two openings run together to form one. To what 
part of genital apparatus of other insects does this double incubation 
sac correspond? I have not yet been able to settle this point, in as 
much as I have only had under observation insects in which the sacs were 
already filled with eggs in course of development, and in which the 
empty and shrivelled ovaries were with difficulty visible. In spite of 
the relatively long duration of their life, the Chleeopses takes no more 
food in the adult state than the other Ephemere. Their mouth is 
only armed with a few soft and incomplete parts. 
“The larve are elongated, very active, armed with feet terminated 
by a single hook. The head, roughly pentagonal in form, bears two 
long antennæ and five ocular spots of which one, odd, is situated between 
the bases of the antennz; the four others are arranged in two pairs, of 
which the posterior furnishes the reticulated eyes of the adult. The 
mouth is provided with a masticatory apparatus, which is well formed. 
The abdomen is formed of ten segments, of which the last bears two 
long filaments provided with a few stiff hairs. The length of the body 
is 0.7 millim., not including the caudal filaments, which are at least as 
long as the body. The cephalo thorax and the anterior part of the 
abdomen contain at birth brilliant globules, which disappear in a day 
Or two. During the first period of their existenee the larve have 
neither trachez nor tracheal branchise. Six days after their birth the 
larvee undergo a first change; their appearance changes but little, but 
on each of the 2nd, 3rd, 4th, 5th and 6th abdominal rings there appears 
a pair of short prominences, each as much developed as the others, the 
rudiments of the future tracheo-branchise. Three days later there is 
another change; the five prominences just mentioned become elongated, 
and a pair of them appear on the first abdominal ring, the trachex also 
become visible. After the third change, the five pairs of tracheo- 
branchiz are well formed and receive the trachez. Those of the first 
ring do not develop completely until the fourth change, and, finally, 
those of the seventh abdominal ring, apparent at the third change, are 
not complete till after the fifth. From that time the larva possesses all 
ats organs,” 
EMBRYOLOGY.’ 
The Corpus Luteum.—The fate of the Graafian follicle of the 
Mammal’s ovary is certainly very remarkable. The well known corpus 
‘ Edited by E. A. Andrews, Baltimore, Md., to whom abstracts reviews and 
Preliminary notes may be sent. 
