ACAEI 0¥ THE GENUS GLYCIPHA.GUS. 273 



I have said that I should not have supposed the creatures to 

 be different sexes of the same animal had I not found them in 

 coitu ; but this I did, not in one case only, but in very numerous 

 instances, so that there cannot be any doubt about it. 



This brings me to another branch of my subject, viz. the satis- 

 factory proof which this species affords that the posterior projec- 

 tion of the females is the bursa copulatrix. In most species of this 

 genus and its close allies, and in the DermaleicM, the coitus lasts 

 a long time, as in the Lepidoptera, with this difference between 

 the Acari and the Insects, that whereas in the latter the pair 

 remain mostly stationary, in the former they keep in almost 

 constant motion ; the female, which is the larger and more 

 powerful creature, dragging its companion. In the present 

 species, G. dispar, the disproportion in the size of the sexes is 

 so great that the female does not drag, but carries the male, the 

 anterior half of the male lying on the dorsal surface of the hind 

 part of the abdomen of the female, which is clasped by the two 

 fi ont pairs of legs of the male, whose two hind pairs, usually 

 directed backward, are now bent directly forward on the ventral 

 surface of the female. Her abdomen is thus clasped by all the 

 legs, and so firm is this grasp that not only may the pair be re- 

 moved to the microscope and placed under a cover glass, and 

 both the dorsal and ventral surface examined without its becom- 

 ing relaxed, but it is even possible to make permanent micro- 

 scopical preparations of tbe.two in situ — one of these preparations 

 being shown on the occasion of reading this paper. The di'awing 

 of the pair in position (PI. XXXV. fig. 8) was drawn from the life 

 with the assistance of such a preparation. This peculiar position of 

 the hind legs, the absence of hairs from the male, and the flatness 

 of its underside, enable the position of the organs to be most 

 clearly seen, and would alone settle the question of the bursa 

 copulatrix if it were still in doubt. There is, however, an addi- 

 tional and interesting piece of evidence. It was pointed out by 

 Haller, in a paper dated iNovember 1879*, that in Tyroglyplius 

 seiiferus the post-anal copulative opening of the female, which 

 is in tbis case a mere pore, not a projection, led by a very short 

 neck into an almost globular receptaculum seminis. This has 

 lately been carefully worked out by Dr. Alfred Nalepa, in the 



* " Zur E'enntniss der Tyrogljphen undVerwandten " Zeitschr. f. wiss. Zool. 

 xxxiv. Ed. p, 288. 



