GE^TERATIOX OF IXSECTS. 391 



With regard to the female organs of the Myriapoda. In the lulus 

 terrestris the ovarium is a simple elongated sac, wilh the exterior 

 surface nodulated by sacculi ; the larger ones, of uniform size, being 

 arranged in a double series. The ova are developed and completed 

 in these sacculi, one in each ; the germinal vesicle here is surrounded 

 by the yolk and vitelline membrane ; upon this is laid the thin layer 

 of albumen and the corion before it passes into the common oviduct. 

 The ova in the earlier phase of development form small projections 

 at the interspaces of the larger and more regularly-sized ovisacs con- 

 taining the more mature ova. The common elongated sac extends 

 from the anal segment forwai d to near the fourth segment, where it 

 divides, and the two vulvae are situated on two scale-like bodies on 

 the under surface of that apodal segment, behind the second pair of 

 legs. A short reservoir for the male semen {spermatheca) commu- 

 nicates with each oviduct. The ovarian tube is situated beneath the 

 alimentary canal ; not above it, as in the Crustacea. If the male 

 apertures on the seventh segment indicate, by the analogy of the 

 Crustacea, the hinder boundaries of the thorax, we see that the more 

 advanced position of the female apertures keeps up that analogy. 

 Another interesting analogy presents itself in the double aperture of 

 the generative outlets and the double intromittent or clasping organs 

 in the male Iulid(B. I allude to the serpent tribe, which these Articu- 

 lata resemble in their length, slenderness, and tortuous movements ; 

 for the serpents alone, amongst Vertebrata, present the double termi- 

 nation of the generative ducts and the double unciform claspers. 



In the Lithobius forficatus the ovarium, a single elongated blind 

 sac, extends from the anal segment to near the middle of the body, 

 and is supported by the tracheal capillaries. It is beset by numerous 

 subpedunculate unilocular bursae, each containing a white globular 

 ovum. These give a granular aspect to the exterior of the ovarian 

 tube ; which tube Leon Dufour suspects to be naturally divided by 

 a median longitudinal septum.* On each side of the termination of 

 the ovarian tube is a racemose colleterium, consisting each of two 

 rows of granular utricules : a common duct and reservoir communi- 

 cates with the oviduct. 



The generative function offers so many distinctive peculiarities in 

 the present aberrant subclass, that I shall conclude my account of it 

 before entering upon the same subject in the typical hexapod insects. 



Some important facts were early recorded relative to the meta- 

 morphoses of the lulidiB by Degeerf and Savi \, and their generation 

 has been very ably and minutely worked out by Newport. § 



* CCLIU. t Ct'LIV, X CLV 4 CCLII. 



c c 4 



