CHAP, xv CLASSIFICATION 385 



308 species, divided among six families. Black-wall's beautiful 

 work, the Spiders of Great Britain and Irelmnl, was published 

 by the Bay Society in 1804. He divides spiders into three 

 tribes, Octonoculina, Senoculina, and Binoculina, according to the 

 number of the eyes, and describes 304 British species, distributed 

 among eleven families. 



His successor in this country has been Pickard-Cambridge, 

 whose work, under the modest title of The /Sy^V'vs of Dow/ 

 (1879-81), is indispensable to British collectors. 



BlackwaLL's division of the order into tribes was evidently 

 artificial, and has not been followed by later Arachnologists. 

 Dufour (1820) founded two sub-orders, Dipneumones and Tetra- 

 pneumones, based on the presence of two or four pulmonary sacs. 

 Latreille (1825) established, and many Arachnologists adopted, a 

 division into tribes based upon habits, Orbitelariae, Eetitelariae, 

 Citigradae, Latigradae, etc., and this method of classification was 

 followed in the important work of Menge, entitled Preussische 

 ^l>i n.nen, which was published between 1866 and 1874. 



Since 1870 determined efforts have been made to grapple 

 with the difficult subject of Spider classification, notably by 

 Thorell and Simon. The latter, undoubtedly the foremost living 

 Arachnologist, writes with especial authority, and it is inevitable 

 that he should lie largely followed by students of Arachnology, 

 who cannot pretend to anything like the same width of outlook. 



It is indicative of the transition stage through which the 

 subject is passing that Simon in his two most important works, 1 

 propounds somewhat different schemes of classification, while in 

 the Histuire naturelle, where his latest vie\\s are to be found, 

 he introduces in the course of the work (juite considerable 

 inodilications of the scheme set forth in the lirst \olunie. 



In that work the order is divided into two sub-orders. 

 AI;ANKAK TIIKKANIOSAK and AKANKAK VHI;AK. the lirst sub-order 

 containing Li/i/i /'.s////.s and the, Mygalidae or Theraphosidae of 

 other authors, while all other spiders fall under the second sub- 

 order. The Araneae verae are subdivided into CRIBELLATAE and 

 EC RIBELL AT AE, according to the presence or absence of "cribellum" 

 and '' calainist rum " (seep. 326) in the female. Important as 

 these organs doubtless are. the ( 'rihellatae do not, appear to form 



1 A rachnides de France (vol. i., published 187 1. H desaraig 



(2nd cd. vol i., ]iulili.>liu(l 1892). 



VOL. IV - C 



