538 CASE or PAETHENOGEIfESIS IK" THE HOTJSE-SPIDEE. 



found adhering to it her first and third leg, which were broken 

 off just below the trochanter. I suppose the tarsi had been 

 caught against the rim of the bottle, and she had dismembered 

 herself to obtain freedom, a common occurreDce with Spiders. 

 Towards the end of March she began to strengthen the supports 

 to that part o£ the web which was her usual resting-place. This 

 was done by spinning from the bottom of the bottle an irregular 

 loose vertical shaft, which was partly covered with the remains of 

 her victims, the threads taking no particular direction. Her web 

 was now still more unlike the cob of her species ; but I have found 

 that other T. Guyonii, when about to lay eggs in the-same-shaped 

 vessel, made the same structure. On the 7th of April, after an 

 absence of three days, I found she had woven the ordinary cocoon, 

 viz. two sheets of silk with the eggs between them. She must 

 have been disturbed, probably by a strong fly, in her first attempts ; 

 for a few eggs were hanging loosely on threads away from the 

 rest. I found her dead on the 10th of May, and put her in 

 spirits ; but I think, from dissection, she died prior to that date. 

 On tlie 7th of June I thought there was some movement in the 

 cocoon, when the two sheets were carefully separated ; then I 

 found that two Spiders were hatched, twelve eggs still retained 

 vitality, while the rest were hard and shrivelled. 



The fertility of this Spider after a confinement of eleven mouths, 

 during which time she twice moulted, can only be explained by one 

 of the following alternative causes: — (1) that she was impreg- 

 nated previous to the casting of the two exuvi^, in an early and 

 therefore immature stage ; (2) that parthenogenesis occurs in the 

 Araneidea. 



The researches of Megnin *, Kramer t, Haller %, and Michael § 

 show that the females of some Acarina, and more especially of 

 the Dermaleichidae, couple with the males prior to their final moult, 

 and that practically there are two stages of sexual maturity : — 

 1st, of the"vulve d'accouplement;" 2nd, of the "vulve de ponte." 

 On the other side, Mr. Beck || and, lately, M. Berlese ^ have 



* 'Les Parasites et les Maladies parasitaires,' pp. 180-220, and Journ. Anat. 

 et Phys. 1872, p. 337, 1873, p. 369, aud 1874, p. 225. 



t G-iebel's Zeit. fur ges. Naturwiss. 3. Folge, 1881, vol. vi. pp. 417-451. 



\ " Ueber d. Bau d. vogelbewolinenden Sarcoptiden," Zeit. f. wiss. Zool. 1881, 

 Bd. xxxTi. p. 366. 



§ " On the Eeproductive System of some of the Acarina," Journ. Quek. Micr. 

 Club, Nov. 1879, vol. v. 



II "A short Description oiAcarus and its Agamic Reproduction," Journ. Micr. 

 Sci. vol. xiv. p. 30. 



^ " II polimorfismo e la partenogenesi di alcuni acari," Bull. Soc. Ent. Ital., 

 ann. xiii. p. 290. 



