Physiology of the Araueidea. 179 



des femelles. Le 16 juin suivant, accouplement de FAraneide 

 mere avec un de ses petits, niale^ provenant de la premiere couvee. 

 Deux cocons formes du 26 au 28 juin. Les oeufs d'un des deux 

 cocons ont eclos le 27 juillet, et il n'en est sorti que des femelles. 

 Les oeufs du second cocon ont eclos le 31 juillet, et il n^en est 

 sorti que des males." The events to which attention is here di- 

 rected are represented as succeeding each other with a degree of 

 rapidity unparalleled in the i*ecords of arachnology. 



It appears that on the 23rd of April 1840 a female Theridion 

 triangulifer deposited in a cocoon a set of eggs which produced 

 young on the 5th of May ; they all proved to be males, and on 

 the 16tli of the following June one of them paired with its pa- 

 rent, which enveloped a set of eggs in a cocoon on the 26th and 

 a second set in another cocoon on the 28th of the same month ; 

 the first set was hatched on the 27th of the ensuing July and 

 produced males only ; the second set was hatched four days later, 

 and from it proceeded females only. 



Now, though many of the Theridia are very short-lived, and, 

 consequently, pass through their several mutations and arrive at 

 maturity earlier than those spiders whose existence is of longer 

 continuance, yet, in my researches into the oeconomy of the Ara- 

 neidea, which have occupied a considerable portion of my leisure 

 hours during many years, an instance of the young of these ani- 

 mals becoming adult in the same season that the eggs were de- 

 posited from which they were disengaged has never come under 

 my observation ; but in the example before us, an egg laid on 

 the 23rd of April is stated to have produced a male spider which 

 on the 16th of the ensuing June was capable of propagating its 

 species. If the small size of spiders on qiiitting the egg be borne 

 in mind, and if it be taken into consideration also that an ad- 

 vance in growth, particularly of the cephalo-thorax and its ap- 

 pendages, is limited to the periods at which the integument is 

 changed, a suspicion can scarcely fail to be induced that there 

 may have been some latent source of error in the observations of 

 M. Doumerc, which it is very desirable should be carefully re- 

 peated. As regards Theridion triangulifer depositing two sets of 

 .eggs at different times, each of which produced young of the same 

 sex only, one males, and the other females, I will merely remark, 

 that hitherto I have had no opportunity of investigating the oeco- 

 nomy of this species ; but that the case is very different with 

 Tegenaria civilis conclusive evidence is not wanting, for I have 

 brought uj) individuals of both sexes from the same set of eggs, 

 ^deposited in a cocoon by this common and widely distributed 

 •pider on the 27th of ^May 1842. 



A passage in the ' Introduction to Entomology,' by Messrs. 

 Kirby and Spence, fifth edition, vol. iv. letter xliv. p. 214, merits 



12* 



