roMliNA t'ol.I.EOK JoIKNAI, OK KNTtJMOUXiV Sti3 



only a i)art of tliciii list" it in i-nptiirini; tlu'ir pn'y, the foniitT must have 

 lifcn tile ])riiiiary utility, and this use varies in amount from tl»> few threads 

 of the Pholeus to the elahorate ejfK >*«<■ of tlie (iltipttivraninm niniiyi rum. 

 Some of the more spe<'ialized ways of utilizing' tin- silk, are hy the hurrow 

 spider for stri'Mtrtiienin^r the walls of the tunnel or hy the tra|>-door spider in 

 its specialized lid. or the Ariailiiu in its remarkahly contrived tuhe. Nothint; 

 can he said deliuitely as to the way in which the weh-nuikin^' lialiit arose, hut 

 it seems pruhahlc that the spinning of a dra^' line was one of the first steps, 

 and the next is nut diflicult to imagine. Working in a limiteil space, the 

 spider wotdd cross and recross this line till somethitiK of a weh was formed, 

 ami if perchance an insect were entangled in it, the process would he complete. 

 The simpler wetis, such as that of the I'holriis, are just those irre^rular nets 

 made of the same kind of silk as the drajr line. In advaru-e of the I'boltua are 

 the !iinyphiida>. the sheet weh weavers, and the Ajjelnida' with the a<ldition 

 of the funnel-shaped retreat. All of these wehs, formed of one kind of silk, 

 are simply to entanfjle the insects until the spider can reach them, hut during 

 the evolution of the weh-uuikinjf hahit, many families have developed special 

 ortrans for producing a viscid silk for holding the insect last. The Theridiida* 

 have the simplest form, a visciil licpiid thrown over the prey, hut then- is a 

 s])ecialized organ, the com!) on the tarsus of the fourth legs, for flinging the 

 silk. Other families use a thread or hand of the viscid silk in making the 

 weh and in these wehs of eond>ined nuiterials, two lines of speeiali7.atiuD are 

 recognized. The first is a simple foundation and a complex structure of the 

 viscid which nuiy he a simple or complex hackled hand. The second, a per- 

 fected founilation and an unspecializcd use of the viscid silk, finds its culmina- 

 tion in the orh- weaving spiilers, the I'lahoridu' anil the Argiojiida-. The steps 

 in the huililing of an orh weh are very interesting. First the outer frame- 

 work, the permanent part, is made, and then in the open space thus formed the 

 radii are stretched. At their converging point the huh is erected and from 

 this a spiral guy line is sjuin upon the radii, to hold them together for the 

 next process. After all this has hecn formed of dry silk, heginning at the 

 outer edge, the spider adds the loops and turns of viscid silk, destmying the 

 spiral line in the process. The remainder of the article is devoted to exam|>les 

 of orh-weaving spiders of ilifTerent kinds ami closes with a tahular arrange- 

 ment of the steps in the perfection of weh-making. 



Ki.izvBKTii .Iack.>^. 



Till', Sl'lDEH HOOK 



J. II. COMSTOCK 



Douhleday, I'age & Co. 



To the general reader as well as to tho.se more i)articularly interestetl in 



zoology, this hook must he of interest. The suh.iect matter covers over 705 



pages and there are also over 7tKt illustrations. .Much of the material included 



is new ami all is clear and well prc.sented. Among the interesting material 



