386 ARACHNIDA ARANEAE CHAP. 



a natural group, some of the families having apparently much 

 closer affinities with certain of the Ecribellatae than with one 

 another. This is especially evident in the case of the cribellate 

 Oecobiidae and the ecribellate Urocteidae (see p. 392), which 

 most authors unite in a single family. 



After all, the larger divisions of the order are not of great 

 importance, and in the present chapter Simon's linear arrange- 

 ment of families will in the main be followed, except for the dis- 

 tribution of the eight families which constitute his Cribellatae l 

 to the positions which a more general view of their structure 

 would seem to indicate. 



Fam. 1. Liphistiidae. Spiders with segmented abdomen, as 

 shown by the presence of a series of tergal plates. Eight spin- 

 nerets in the middle of the ventral surface of the abdomen, far 

 removed from the anal tubercle. Sternum long and narrow. 

 Eight compact eyes on a small eminence. Four pulmonary stigmata. 

 This Family includes a single genus and two species of large 

 spiders (about two inches in length), one from Penang and one 

 from Sumatra. Very few examples have been found, and these 

 are more or less defective and in bad condition. In some respects, 

 especially the distinct segmentation of the abdomen, this genus 

 much more nearly approaches the Pedipalpi than do any others 

 of the order. No other spider possesses more than six spinning 

 mammillae, but it is possible that eight was the more primitive 

 number, and that the " cribellum " (see p. 326) of the so-called 



Cribellate spiders is derived from 



the pair now possessed by Liphistius 



alone. 



Some Arachnologists consider the 



genus Liphistius so different from 

 FIG. 201. Profile (nat. size) and all other spiders as to constitute in 



ocular area (enlarged) of Liphistius i( . gelf ft gub . order for which on 

 desuitor. ' 



account of the position of its spin- 

 nerets, the name MESOTHELAE has been suggested, all other 

 forms falling into the sub-order OPISTHOTHELAE. 



Fam. 2. Aviculariidae. (Mygalidae). 2 Spiders with inde- 



1 Simon's Cribellatae comprise Hypochilidae, Uloboridae, Psechridae, Zoropsidae, 

 Dictynidae, Oecobiidae, Eresidae, Filistatidae. 



2 The Spider genus Mygale was established by Walckenaer in 1802, but the 

 name was preoccupied, having been used by Cuvier (Mammalia) in 1800. 



