270 DIVISION III. ARTICULATED ANIMALS.—CLASS IV. INSECTA. 
to which they are fastened. They deposit a prodigious number of eggs, 
discharging them from the mouth, according to M. Chabrier. Their mul- 
tiplication upon the ox and horse is sometimes so great that these animals 
perish from exhaustion. The tarsi are terminated by two ungues inserted 
upon a plate, or are united at the base upon a common peduncle. The 
ancients appear to have known these animals under the name of Ricini. 
They are our well-known Ticks, one species of which attaches itself to 
sheep, and another to oxen. It is sometimes found embedded in the skin, 
and I have seen them over a half inch in length. 
CLASS IV. OF ARTICULATA. — INSECTA. 
There is no department of the animal kingdom which offers a more varied 
and interesting field for investigation than the Insect World; nor is there 
any class of animated creatures that exhibits, in a more wonderful manner, 
the wisdom, and condescension, and benevolence of the Almighty, than those 
tiny beings that creep and flutter through their little life, fulfilling, for the 
most part, in a few months, the mission and end for which Nature called 
them into existence. The gorgeous and beautiful colors of some, the 
extraordinary intelligence of others, and the remarkable structure and hab- 
its of all, always excite sentiments of admiration, and often feelings of 
amazement. 
M. Louis Figuier furnishes the following brief but very correct descrip- 
tion of the class : — 
“Tf we wish to characterize insects by their exterior aspect, we might 
consider them as articulate animals, whose bodies, covered with tough and 
membranous integuments, are divided into three distinct parts: the head, 
provided with two antennw, and eyes and mouth of very variable form; a 
trunk, or thorax, composed of three seements, which has underneath it 
always six articulated limbs, and often above it two or four wings; and an 
abdomen composed of nine segments, although some may not appear to 
exist at first sicht. 
“If, in addition to these characteristics, one considers that these animals 
are not provided with interior skeletons; that their nervous system is formed 
of a double cord, swelling at intervals, and placed along the under side of 
the body, with the exception of the first swellings, or ganglions, which are 
under the head; that they are not provided with a complete circulating sys- 
tem; that they breathe by particular organs, termed tracher, extending 
parallel to each other along each side of the body, and communicating with 
the exterior air by lateral openings termed spiracles; that their sexes are 
