Structure and Functions of the Araneidea. 341 



less conspicuous on male than on female spiders, the occasions 

 for their employment being fewer and of minor importance in 

 the former than in the latter sex. 



The prevalent opinion, that the very remarkable snare of 

 Mithras paradoxus does not afford any evidence in its con- 

 struction of the action of the fourth pair of spinners and the 

 calamistra with which this spider is provided, is probably erro- 

 neous ; for I have reason to believe that the transverse lines 

 attached to the four radii in the snare of this species are formed 

 by the agency of the calamistra in passing over the extremities 

 of its spinners 5 and this agency is undoubtedly exercised in 

 forming the external convex covering of its cocoon. A species 

 of Mithras which inhabits the United States of North America 

 evidently employs its fourth pair of spinners and calamistra in 

 the fabrication of its cell. 



Now, as I am disposed to attach much importance to the 

 habits and economy of spiders with reference to their system- 

 atic arrangement, the fact that species provided with calamistra 

 are always found to possess the additional spinners, and that 

 these parts constantly cooperate to produce results affecting 

 their economy in a very obvious manner, has not, I apprehend, 

 had that consideration bestowed upon it by arachnologists to 

 which it appears to be entitled. 



The late Mr. Richard Beck communicated to the Microsco- 

 pical Society of London, in the year 1861, some remarks on 

 the formation of the viscid spiral line in the snare of Epeira 

 jdiadema^ commonly denominated the garden spider. In this 

 paper, of which I have merely seen an abstract, tlie following 

 statement occurs : — "With only a pocket-lens I could distinctly 

 see that the viscid lines, as first drawn from the abdomen, were 

 not dotted. On a careful examination with the microscope, 

 the thread at first appeared only slightly thicker than an un- 

 gummed line ; but after a very short time undulations appeared, 

 and subsequently, at the most regular distances, the viscid 

 matter formed into alternating large and small globules. The 

 whole process is a beautiful illustration of molecular attraction." 



Without questioning the accuracy of Mr. Beck's observa- 

 tions, several difficulties present themselves in connexion with 

 his explanation of this curious subject, that carefully conducted 

 investigation alone can dispel. To some of these difficulties I 

 shall now direct attention. 



The fine elastic line on which the viscid globules arc distri- 

 buted is consolidated] but it is per[)lexing even to conjecture 

 how this consolidation is effected, since, according to Mr. l^eck, 

 the line is suiTOunded by a viscid fluid as it is drawn from the 



