Mr. J, Lubbock on the Generative Organs in the Annulosa. 409 



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

 without any arrangement. In the youngest Furkinjean vesicles of 

 Lithobius there are about seven nuclei, each 3^00*^1 ^^ ^" inch, or 

 thereabouts, in diameter. As the eggs increase in size these macula; 

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

 more numerous. This is very remarkable, nothing hke 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 Furkinjean vesicle, may generally be seen in it. This 

 vesicle is probably homologous with the vitelline vesicle oi Arthrono- 

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

 bling that of lulus*. The eggs of Cryptojis 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 spermathecae of the females examined by 

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

 Arthronomalus is spherical. The yelk-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 Furkinjean 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. 

 Occasionally even the macula was thus prciduced. It appeared 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 yelk, 

 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 Fhalangidse I examined the genera Phalangium, Nemastoma, 

 Opilio, and Leiobunus, 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 

 that the "testes are formed by a cluster of elongated . . . csecal tubes;" 

 and this opinion has been generally adopted, though from the structure 

 and contents of these tubes it is evident that they are rather to be 

 regarded as accessory glands. Leydig found among these tubes one 

 longer than the rest, and described this, which is in fact the ductus 

 ejaculatorius, as the true testis. The true testis, however, had been 

 misunderstood, but not overlooked. It is described by Treviranus, 

 Tulk, Leydig, and others, and being present only in the male sex, 



* 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 unsymmetrical in this respect. 



Ana. ^ Mag. N. Hist. Ser. 3. Vol. viL 27 



