58 
Subdivisions of Articulata. 
Sect. I. Arthropoda or True Articulates,—Those articulates having 
the body distinctly divided into segments; furnished at some 
time of life with articulated locomotive organs; the nervous 
system consisting chiefly of a double claim of ganglia run¬ 
ning along the ventral side. 
1. Class Insecta .—Three pairs of legs in the perfect state; abdomen 
destitute of limbs; one pair of antennae; head, thorax and 
abdomen distinct; usually with two pairs of wings; air 
breathers. Contains all the true insects. 
2. Class Myriapoda .—Legs numerous, usually more than eight pairs; 
head distinct, remainder of the body composed of similar 
segments; one pair of antennae; air breathers. 
Contains the centipedes, millipeds, etc. 
3. Class Arachnida .—Four pairs of legs; no true antennae; head 
and thorax amalgamated into one piece; breathing various. 
Contains spiders, ticks, mites, scorpions, etc. 
4. Class Crustacea .—Locomotive appendages more than eight; two 
pairs of antennae; head and thorax amalgamated into one 
piece; water breathers. 
Contains the lobsters, crawfish, shrimps, crabs, sand-fleas, 
etc. 
Sect. II. Vermes or Worms.—Division of the body into segments 
, usually not so distinctly marked and sometimes wholly want¬ 
ing; never furnished with articulated locomotive appenda¬ 
ges; nervous system usually less perfect than in the preced¬ 
ing section. 
5. Class Annelida .—Body showing segmentation but not so dis¬ 
tinctly marked as in the preceding section; without any 
distinct head in the true sense; the nervous system as in 
the preceding section. The segments very numerous and 
similar, except those at the anterior and posterior extremi¬ 
ties of the \>ody. 
Contains the leeches, earth-worms, sea-worms, etc. 
6. Class Scolecida (Helmintha or Entozoa).—Body usually without 
apparent segmentation, though in some cases this is dis¬ 
tinct; without locomotive appendages; the nervous system 
very imperfect or wanting; with the exception of two or¬ 
ders, are internal parasites. 
Contains the tape-worms, cyst-worms, flukes, trichina, rib¬ 
bon-worms, thorn-headed-worms, hair-worms, round-worms, 
wheel animalcules, etc. 
We shall have occasion to refer to 'species of but three of the 
classes here mentioned, to-wit: Class Insecta or Insect class; Class 
Arachnida or Spider class; Class Scolecida or Intestinal Worm class. 
As I have in a previous report noticed the orders of insects, it is un¬ 
necessary for me to do so here. 
The Class Arachnida is usually divided into three orders, as fol¬ 
lows: 
