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appear to subdivide, at any rate they become continually smaller and 

 more numerous. This is very remarkable, nothing like it taking 

 place in the other genera. When the egg has attained a certain size, 

 but before it has begun to darken, a small vesicle, about one-third of 

 the size of the Purkinjeari vesicle, may generally be seen in it. This 

 vesicle is probably homologous with the vitelline vesicle ofArthrono- 

 malus, c. It soon disappears, and is replaced by a " patch " resem- 

 bling that of lulus*. The eggs of Cryptops are narrow. The 

 macula differs from that of Lithobius, and agrees rather with that of 

 Glomeris, in consisting of two unequal separate bodies. To the 

 description of the spermatophores given by M. Fabre, I have nothing 

 of importance to add. The spermathecce of the females examined by 

 me contained' only filiform spermatozoa. The form of the eggs in 

 Arthronomalus is spherical. The yolk-nucleus is very apparent, and 

 has at first all the appearance of a vesicle. Globules gradually appear 

 in it, and it loses its distinct outline. 



The development of the eggs in Geophilus is much like that of 

 Arthronomalus. The principal peculiarity observed was in the 

 structure of the Purkinjean vesicle, which appeared to consist of two 

 different substances, one surrounding the other. The inner substance 

 was generally produced in the form of a peninsula at one or two places, 

 almost through the outer substance. This latter was of more regular 

 outline, but sometimes partially followed the same outline. Occa- 

 sionally even the macula was thus produced. It appeared to be that 

 the projecting parts gradually became pinched off from the main 

 portion, and thus formed certain irregularly rounded bodies, which 

 could in most eggs be indistinctly discerned in the homogeneous yolk, 

 and were probably homologous with the vitelline vesicle of Arthrono- 

 malus. A somewhat similar phenomenon has been described by 

 Leuckart as occurring in the eggs of Aphis rosce. 



In the Phalangidse I examined the genera Phalangium, Nemastoma, 

 Opilio, and Leiobumus, in all of which the process of egg-development 

 was similar, and resembled that already described as occurring in 

 Polydesmus. The structure of the male generative organs has, how- 

 ever, been entirely misunderstood by all preceding writers. Tulk states 



* The number of labial teeth, which is a point generally used as a specific 

 character, varies in many individuals; out of twenty-eight specimens examined, 

 nine were unsym metrical in this respect. 



