294 MR. A. D. MICHAEL ON THE VAEIATIONS IN THE 



retaining the club-shape ; it contains minute highly refractive particles, which are to he 

 regarded as the true spermatozoa, the whole cell being, he considers, a spermatophore, 

 although he usually calls it a spermatozoon ; he also thinks that the cell breaks up 

 and is transformed within the female. 



The Mode of Coition. 



I place this here, apparently somewhat out of order, because I think it will enable 

 some part of what I have to say relative to the female organs to be more readily 

 understood. 



The coition has been carefully watched by me in four species, viz. Gamasus terribilis, 

 Lcelaps cuneifer, Ilcemogamasus hirsutus, and Gamasus crassus, not only once but in 

 several instances, more especially in the cases of the firstly and thirdly named species. 



In 1886, in the paper upon the then newly discovered Gamasus terribilis (p. 288, note t), 

 I for the first time described this process, which I think will be found exceptional in 

 nature and of considerable interest. I had, however, then only observed it in a single 

 species and during the short period that elaj^sed between the discovery and the publication 

 of the paper. I have since investigated the matter more thoroughly and have compared 

 other species, with the result that I am able to describe it much more fully and in some 

 respects more accurately ; and that I find that this very singular process is not confined 

 to Gamasus terribilis, but is common to at least a section of the family. Of course I 

 cannot say whether it is universal, but it has been the method in all species w^hich 

 I have been able to observe sufficiently well since I first noticed it ; but these species 

 are much too few to generalize upon. 



I will describe the process in Ilcemogamasus hirsutus, a species in which I have 

 watched it several times, and have been fortunate in obtaining clear observations and in 

 killing and examining the creatures at diff'erent stages. 



The male, which is smaller than the female, approaches her usually from the side ; 

 he occasionally jumps upon the dorsal plate of the female, but the other is the commoner 

 mode. In either case the male clasps its legs round two of the legs of the female, both 

 on one side ; the legs seized have usually been the 3rd and 4tli, but sometimes the 

 2nd and 3rd. The male, having secured a firm hold of the legs of the female, slowly 

 turns over so that his dorsal surface is downward, then sli2)s right under the female, 

 keeping further back than the female, so that nearly half the body of the male projects 

 behind the female ; the male passes its fourth pair of legs upward behind the posterior 

 edge of the abdomen of the female and lays its tarsi on the dorsal surface of her 

 abdomen, thus obtainini]? a firm hold. "What looks like a hvaliue sac or bubble then 

 appears in the mouth of the genital aperture of the male ; this sac is somewhat rapidly 

 distended, but still takes some little time, varying in diff'erent cases, before it attains its 

 full size. If the creatures be now suddenly killed (which must be done in an instan- 

 taneous manner either by chloroform ejected from a pipette or else by boiling water), 

 this sac, which I propose calling the spermatic capsule (capsula spermatis) and shall 

 refer to in future by that name, is found in the mouth of the genital opening of the 

 male, the end of the capsule only being attached to the opening, and the other part of 



