119 



In the more advanced eggs of Glomeris, the macula of Wagner is 

 double, one being much smaller than the other. 



The ovary of lulus has been described by Newport ; the specimens 

 which he examined had, however, been submitted to the action of 

 spirits of wine, and were therefore altogether unsuitable for histolo- 

 gical examination. The egg-follicle did not contain any large vitelli- 

 genous bodies like those of Glomeris, nor could I see in it a vitelline 

 vesicle like that of Arthronomalus ; but it very generally contained, 

 when the yelk was beginning to darken, a patch resembling that 

 which appears to result from the small vitelline vesicle of Lithobius. 

 In both these genera the eggs in all stages of development are mixed 

 together without any regular arrangement. The macula appears to 

 be generally double, as in Glomeris. In the genus Polydesmus, 

 however, where, as in all Chilognaths, the eggs are arranged on a 

 double stroma, situated at the lower side of the ovary, the smaller 

 eggs are on the central parts of the stroma, and the more developed 

 ones lie towards the sides. In appearance the ova offer a great 

 contrast to those of lulus, and particularly of Glomeris, since the 

 margin of the yelk has all the appearance of being bounded by a 

 distinct membrane, though I am not convinced that this is really the 

 case. I have not yet made out in Polydesmus anything corresponding 

 to the "patch" of lulus. The macula appears to be always single. 

 It often contains vacuoles. 



The yelk of mature eggs consists, 1st, of globules about 50 6 00 th 

 of an inch in diameter ; 2ndly, of greenish bodies about 4 fa O th in 

 diameter; and Srdly, of a clear, more or less viscid substance. 

 By the month of October most of the females have laid their first 

 lot of eggs ; after which another set immediately begin to be deve- 

 loped. M. Fabre does not appear to have seen the spermatozoa 

 of Polydesmus. They are small, elliptical bodies about -ginn^n 

 of an inch in length, and containing a bright nucleus. M. Stein 

 appears to be the only naturalist who has hitherto described them 

 from personal observation, but he does not allude to the nucleus. 



In Lithobius, Cryptops, GeopMlus, and Arthronomalus, the eggs 

 form a single series ; large ones and small ones lie next to one another 

 without any arrangement. In the youngest Purkinjean vesicles of 

 Lithobius there are about seven nuclei, each y-gV^th of an inch, or 

 thereabouts, in diameter. As the eggs increase in size these maculae 



