132 ARACHNIDA. 



Consisting of the families Solpuyida, Cheliferida, and 

 Phalangiidee, or harvest spiders.* 



ORDER IV. 



Monomerosomata of Leach, or those trachean species which 

 have the body formed of a single segment, the abdomen pre- 

 senting no traces of articulation, and the moth either suc- 

 torial, or furnished with concealed didactyle chelicera. This 

 order consists of the very extensive Linnaean genus Acarus, 

 or mites, divisible into various families. 



SECTION III. 

 ORDER V. 



Podosomata of Leach, or the Aporobranchia of Latreille. 

 These singular insects are marine ; they are not furnished 

 with distinct spiracles, so that it is probable that respiration 

 is effected by portions of the external covering of the body 

 possessing the properties of branchiae. The body is linear, 

 and seems, as it were, to be composed only of the union of 

 the legs; the mouth is tubular and porrected; and the 

 females are furnished with an additional pair of legs, which 

 serve only for carrying the eggs. This order consists of two 

 families, Pycnogonidie and Nymphonidte. 



ORDER I. D1MEROSOMATA. 



This order corresponds with the Linnsean genus Aranea, to 

 which Latreille gave the name of Filettses or Spinners, Mac- 

 Leay that of Araneidte, and Leach that of Dimerosomata. 

 The name of Aranea has not, however, been dropped, but has 

 been employed to denominate the modern genus, consisting 

 of the domestic spider, Aranea domestica of Linnaeus. 



* In order to preserve the order of the mites entire, as su^ested by Dr. 

 Leach in the Supplement to the Encycloiwedia Hritannica, I have been 

 compelled to establish a new order for the reception of the remainder of 

 the trarhean specirs, which 1 have named from the comparatively ob- 

 scure, articulation of the abdomen._ 



