162 M. Fabre on the Development of the Myriapoda. 



XIV. — Researches on the Development of the Myriapoda. 

 By M. Fabre*. 



The male and female sexual organs in the different genera of 

 the Chilognatha exhibit anatomical peculiarities of which it is 

 difficult to give a succinct account. In all the genera observed 

 by M. Fabre {Polydesmus, lulv^, Craspedosoma, Glomeris, Pol- 

 lyxenus) the vulvae open at the base of the second pair of legs, or 

 between this pair and the third ; the orifices of the male organs 

 also occur in the vicinity of the second pair of feet, or at their 

 base. In Pollyxenus alone, the spermagenous canals open into 

 two enormous penes, longer than the legs and of a greater dia- 

 meter than the largest joint of these. 



Fecundation takes place in the usual way in Glomeris and 

 PollyxenuSy by the contact of the male and female organs. On 

 the contrary, it is effected in a very singular manner in the 

 Polydesmi and lull. The male possesses a copulative organ, 

 which in Polydesmus is formed at the expense of the first pair of 

 feet of the seventh segment. No communication exists between 

 the spermagenous gland and this apparatus. The male seizes 

 the female with his jaws at the back of the neck, then turns her 

 over, and applies his belly to hers. In this position he passes 

 her a little in front ; his mouth is applied to the back of the 

 neck of the female, whilst the latter seizes the throat of the male 

 with her jaws. The copulative apparatus is then placed in front 

 of the vulvae, which receive it. The copulation lasts about a 

 quarter of an hour. The male soon afterwards sets out in search 

 of another female, and the female admits the advances of another 

 male. By attentively observing a male just after he had quitted 

 a first female, M. Fabre saw him elevate the anterior part of his 

 body, and bending it into the form of an S, bring together the 

 second and seventh segments, that is to say, bring his genital 

 apertures in contact with his copulative apparatus. This man- 

 oeuvre, which exactly resembles what takes place in the Ara- 

 neida and Libellula, is repeated after each copulation, and it is 

 only after its accomplishment that the male begins his search 

 for another female. 



The Chilognatha present considerable differences as regards 

 their development. M. Fabre has been unable to observe the 

 eggs of Polydesmus complanatus, but he has found young not 

 more than | mill, in length, and furnished with only three 

 pairs of feet. Each pair of feet was supported upon a different 

 segment, and these legs corresponded with those which, in the 

 adult, are also placed singly upon the first, third and fourth 



* Abstract from the Annales des Sciences Naturelles, [4.] vol. iii. 1855. 



