300 MR. A. D. MICHAEL ON THE VARIATIONS IN THE 



types, it will be seen by PI. XXXIV. figs. 18, 49, 53, &c. that the sacculus and cornu 

 usually contain a number of loose bodies, varying in quantity and mixed up with a thickish 

 fluid and granular or minutely filamentous matter. If the testes of the males of these 

 respective species be examined, and the most mature spermatocysts be compared with the 

 bodies contained in the sacculus of the female and its cornu and diverticula, it is impossible 

 to avoid noticing the extreme similarity of the two : those in the sacculus &c. are usvially 

 a little smaller than those in the testis, and show signs of having been subjected to 

 rather more pressure ; often they have burst and are mere empty sliells, but the perfect 

 ones retain the shape and appearance of the male spermatocysts. If a male II. hirsutus 

 be killed at that stage of the coitus when the spermatic capsule has been filled but not 

 discharged, and if the capsule be allowed to discharge upon a glass slip and its contents be 

 compared wdth those of the sacculus of a female freshly killed, immediately after the com- 

 pletion of the coitus, the identity of the two cannot be doubted (PI. XXXII. figs. 24, 25). 



In Lalaps vacua the commonest form of the ripe spermatocysts in the testis of the 

 male is rather special; it is Avhat I believe is knowai as the "curved dumb-bell" 

 shape in sponge-spicules (PL XXXIII. figs. 27, 28). This is also the commonest form 

 amongst the bodies found in the sacculus foemineus, and the two agree in other respects 

 besides form. It is indeed a fact that in all species examined the spermatocyst in the 

 male testis has an appeai-ance more or less peculiar to the species ; and that, in spite of 

 slight variation, the bodies in the sacculus usually fairly correspond to the ripe spermato- 

 cysts ; also that if the latter can be obtained from the spermatic capsule of the male and 

 from the sacculus of tlie female immediately after coition that resemblance amounts to 

 identity as far as I have been able to investigate the matter. There are, however, some 

 species, such as Lcelaps ctmeifer, Holoiaspis montivagus, Ilolotaspls marglnatus, &c., 

 wliere the sacculus never contains spermatocysts, but only fine granular matter if 

 anything, which may or may not be spermatozoa ; but in these species there generally is 

 not any connection between the cornu and the camera spermatis. 



It may, I think, therefore safely be said that the contents of the sacculus are the 

 products of the male genital organs. 



In cases where the sacculus has contents but they are small in amount, which most 

 usually occurs where the creature is oldish and the ova very fully developed, or the 

 ovary nearly or partly exliausted, the whole contents will generally be found collected 

 in the cornu. If the organs be fuller, then the sacculus itself and, in //. hirsutus, the 

 great globular diverticula are amply supplied, occasionally almost full. If the last- 

 named species be killed immediately after coitus, then the rami will be found to be full 

 also ; but the contents, in the cases I have seen, very soon slip out of the rami into 

 the sacculus. I have not been able to obtain //. horrklus in coitu. 



The question arises, how do the spermatocysts get into the sacculus ? There appear to 

 b(! only tw^o possible methods- — the one that they are ejected from the spermatic capsule 

 into the vagina, pass theuce all along the oviduct, through the camera spermatis and 

 perhaps part of the ovary, thence into the cornu, and then into the sacculus and its 

 diverticula, and even into the rami, whence they finally retu]-n, as required, by the same 

 road to the camera S2)ermatis. This seems an extremely elaborate and not very probable 



