CHAPTER XIII. 
The Worm-Like Animals,— Subkingdom VERMES. 
Although it is convenient to have a single group in which to include the 
various kinds of worm-like animals, it has been frequently pointed out that there 
is no natural sanction for such an arrangement, and that it is highly probable they 
ought to be divided into several subkingdoms. Accordingly, the present division 
of the animal kingdom must be regarded as a convenient receptacle in which to 
place such Invertebrates as cannot be readily assigned to any of the other sub¬ 
kingdoms. This being so, it will be evident that it is only possible to describe this 
assemblage of heterogeneous elements by stating that the various classes into 
which it is divided resemble each other in the negative feature of not possessing 
the characters distinctive of any of the other groups. 
Bristle-Worms, or Annelids, —Class Annelida. 
The more highly organised members of this group show unmistakable points 
of affinity with the arthropods, such as Apus amongst the Crustacea, and Peripatus, 
which aj)proaches the Centipedes. It is possible, however, to mention certain 
characters, which, so far as known, serve to distinguish the bristle-bearing worms 
from the arthropods. In 
the worms the jaws, when 
present, are not modified 
appendages, but are merely 
horny skeletal pieces devel¬ 
oped from the walls of the 
front end of the alimentary 
canal; the appendages,when 
present, are not segmented, 
but merely unjointed pro¬ 
cesses of the sides of the 
body, and certain parts of 
the body are ciliated, or 
beset with fine hair - like 
group OF bristles of an annelid (enlarged 100 times). threads, such threads be in O' 
seldom found at any stage in 
the life-history of an arthropod. To distinguish the annelids or chtetopods Jrom 
the groups that follow, it may be said that there is usually a distinct prostbmium, 
or lobe in front of the mouth, that definitely arranged bristles are iirtplanted in 
