478 SUPPLEMENT 



composed of the same material. It is round, white, formed 

 of a single stratum, and the tenuity of its walls allows the 

 egg to be perfectly well distinguished. Clerk has counted 

 about one hundred and forty of them. They are the size of a 

 grain of beet-root, spherical, of a clear shining white, with 

 white circles on one of the sides. They are exceedingly 

 smooth, and when placed on paper they roll like little drops 

 of mercury. They are seen to go equally from one side to the 

 other in the cocoon, not being agglutinated. The female 

 fixes herself in the midst of the packet of leaves, to watch for 

 the preservation of her posterity. Clerk tells us that the 

 young are born towards the end of July. 



It is more particularly to the species of the genus Tho- 

 Biisus, that Europeans give the name of crab-spiders. They 

 are seen running on the ground, climbing on the bushes, on 

 plants, and even on elevated trees, from which they often 

 descend by means of a thread which they unwind, and by 

 means of which they can reascend. Accordingly Lister has 

 compared them to rope-dancers. Contracting their feet against 

 their body, they balance themselves in some sort, in the air, 

 impress a movement on their thread, and direct it as if nature 

 had given them wings and oars. Degeer also tells us, that 

 these aranei'des unwind always in vi'alking, a thread which is 

 attached to the place where they were seated. They are 

 again to be met with in the corollae of flowers, where they 

 seize the little insects which come to settle. The Thomisus 

 tigrinus is very common on the stems of trees. Clerk has 

 seen the Thomisus cristatus, which he preserved in a box, 

 make at one of its angles a little web as thin as paper. It 

 appears, however, certain, according to the observations of 

 other naturalists, that the Thomisi do not weave nets for the 

 purpose of surprizing their prey, which they take by running, 

 or they wait patiently until it imprudently approaches within 

 their reach. M. Walckenaer tells us that thev introduce 



