224 Mr. J. Blackwall on the Structure ^ Functions 



served on one, when five, six, or seven only are to be seen on the 

 other; and this remark is applicable, not to the inferior spinners 

 alone, but to the intermediate ones also, which, in mature individuals, 

 are further modified by having the extremities of the terminal joints 

 directed downwards at right angles to their bases. The same law of 

 development holds good as regards the papillae connected with the 

 inferior spinners of Drasttus cupreus and Drassus sericeus, and 

 though their number is not uniformly the same even in adults of 

 either of these or the preceding species, yet the two minute ones 

 belonging to each mammula are present invariably *. 



The superior spinners of many spiders are triarticulate ; and when 

 the terminal joint is considerably elongated, thickly clothed with 

 hairs, and tapers to a point, the papillae, in the form of hair-like tubes 

 dilated at the base, are commonly distributed along its inferior sur- 

 face, as in the case of Agelena labyrinthica^ Tegenaria domestical and 

 Textrix lycosina. This deviation from the prevailing structure has 

 induced Lyonnet, Savigny, Treviranus, Audouin, and other skilful 

 zootomists, who have failed to detect the papillae, to regard the su- 

 perior mammulae, thus modified, as anal palpi, and to deny that they 

 perform the office of spinners ; but if these parts be carefully ex- 

 amined with a powerful magnifier in living specimens during the ex- 

 ercise of their function, the fine lines of silk proceeding from the 

 papillae cannot fail to be discerned, and a correct knowledge of their 

 external organization may thus be obtained. Not being aware, ap- 

 parently, of the publication of this discovery in the ' Report of the 

 Third Meeting of the British Association for the Advancement of 

 Science, held at Cambridge in 183S,' p. 445, Baron Walckenaer, in 

 the Supplement to the second volume of his ' Histoire Naturelle des 

 Insectes Apteres,' p. 407, has ascribed it to M. Duges, whose obser- 

 vations on the subject in the ' Annales des Sciences Naturelles,' se- 

 conde serie, t. vi., Zoologie, p. 166, were not published till 1836. 



One of the most striking peculiarities in the structure of the Cini- 

 JlonidcE, which serves to distinguish them from all other animals of 

 the order Araneidea at present known, is the possession of a fourth 

 pair of spinners. These spinners are shorter and further removed 

 from the anus than the rest, being situated at the base of the inferior 

 intermediate pair, by which they are almost concealed when in a state 

 of repose. Their figure is somewhat conical, but compressed and 

 truncated, so that the base and apex are elliptical with long trans- 

 verse axes. Consisting of a single joint only, each is connected with 

 the other throughout its entire length, the extremity alone being 

 densely covered with exceedingly minute papillae, which emit the 

 viscous matter that is formed by the calamistra into a delicate tor- 

 tuous band constituting a portion of every flocculus in the snares of 

 these spiders, and chiefly imparting to them their most important 

 property, that of adhesion f. 



Arachnologists have not bestowed that degree of attention on the 



* Transactions of the Linnaean Society, vol. xviii. p. 219—224. 

 t Ibid. pp. 223, 224, 606. 



