482 Miscellaneous. 



the digestive tube is burst, so that the nerves are detached behind 

 the last nervous ganglion which occupies the seventh abdominal 

 ring. These observations led me to study the female genital 

 apparatus, which ought to be constructed with a view to the internal 

 development of the eggs. Almost the whole of the body of the 

 female is occupied by two huge sacs attached, the one to the other, 

 along the middle line ; the vertical partition which separates them 

 is traversed by numerous tracheae. These sacs extend over the 

 whole abdomen, with the exception of the last two segments, and 

 reach as far as the head, occupying in the three thoracic rings 

 almost the whole of the space left free by the muscles of the wings 

 and legs. Beneath them is the digestive tube, reduced to a canal 

 with a thin and delicate wall, and the nervous chain. These two 

 sacs open on the outside, each by a distinct orifice pierced in the 

 membrane which joins the seventh abdominal ring to the eighth, 

 and, as already described, at the moment of the exit of the larvae 

 these two openings run together to form one. To what part of the 

 genital apparatus of other insects does this double incubation sac 

 correspond ? I have not yet been able to settle this point, inasmuch 

 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 ChJoeopses take no 

 more food in the adult state than the other Ephemera). Their 

 mouth is only armed with a few soft and incomplete parts. 



The larvae are elongated, very active, armed with feet terminated 

 by a single hook. The head, roughly pentagonal in form, bears two 

 long antennae and five ocular spots, of which one, odd, is situate 

 between the bases of the antennae ; 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 

 cephalothorax 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 existence the larvae have neither tracheae nor 

 tracheal branchiae. Six days after their birth the larvae 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-branchiae. 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 tracheae also become visible. After the third change, the five 

 jtairs of tracheo-branchiae are well-formed and receive the tracheae. 

 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 its organs. I hope to be able to pursue 

 these investigations up to the adult stage. — Comptes Bendus, 189(3, 

 torn, cxxiii. pp. 705-708. 



