Wile 
The Classification of Arachnids. 
I eapaisenry ose have long looked forward to a day when the 
| systematic arrangement of living creatures will exhibit the real 
relationship which they bear to one another. All honest classificatory 
work helps science to realise this great ideal, but much is of the nature 
of raw material which may long remain without apparent use. Occa- 
sionally, however, we meet with contributions which seem to add 
considerably, and at once, to the progress of the work ; and such are 
several recent memoirs on the spiders and their allies. 
In 1851, Schiédte described a new genus of Malayan spiders, 
‘Liphistius, of most remarkable structure. This genus was at first 
classed with the Territellariz—the tribe which includes the trap-door 
species, and the well-known large hairy ‘ bird-killers”’ of the tropics. 
More recently Thorell has considered that the genus should form a 
tribe by itself, but be included with the Territellariz in the sub-order 
Tetrapneumones, or spiders with four lung-sacs; and now Pocock 
(1) gives good reasons for assigning to Liphistius a s'ill greater classifi- 
catory value, and placing it in solitary grandeur over against all other 
known spiders. Several striking characters seem to support this 
view. The abdomen in other spiders has lost nearly all traces of 
segmentation, but Liphistius exhibits nine dorsal and two ventral 
sclerites. The spinning-mammille, which in other spiders leave their 
embryonic position as ventral appendages of the abdominal sternites 
behind the lung-sacs, and migrate to the extreme apex of the abdo- 
men, retain in Liphistius their primitive place beneath the middle of 
the abdomen. This latter character suggests the names proposed by 
Pocock for his new divisions, the species of Liphistius being called 
Mesothele, and other spiders Opisthothele. His primary division 
of these latter tallies with the old classification into Tetrapneumones 
and Dipneumones, but he agrees with Simon that the relationships of 
a genus (Hypochilus) of four-lunged spiders are with the latter rather 
than with the former group, and, therefore, suggests the terms 
Mygalomorphe and Arachnomorphe to supersede those time- 
honoured names. In all spiders of the latter group (except Hypochilus) 
the hinder pair of lung-sacs are replaced by trachee. Liphistius 
agrees with the Mygalomorphe in having four lung-sacs, but, in 
several points, it shows affinities with the other division. Alone 
