CRUSTACEA. 779 
deration. The English sailors and soldiers, who were obliged to walk in those 
countries through marshy grounds, talked with terror of the number of leecnes 
that infested them on their march. Even in some parts of Europe, they 
Increase so as to become formidable. Sedelius,a German physician, relates, 
that a girl of nine years old, who was keeping sheep near the city of Bomst, 
in Poland, perceiving a soldier making up to her, went to hide herself ina 
neighboring marsh, among some bushes; but the number of leeches was so 
great in that place, and they stuck to her so close, that the poor creature 
expired from the quantity of blood which she lost by their united efforts. 
Nor is this much to be wondered at, since one of these insects, of a large 
size, will draw about an ounce of blood. 
CLASS VI.—CRUSTACEA. 
Invertebral animals, with a crustaceous, and more or less horny covering, pro- 
vided with articulated members, distinct organs of circulation, and respiring 
by bronchia. 
Tue animals of this class were known to the Greeks under the name of 
Lalexootoaxos, as designating marine animals, of which the exterior envelope 
was much less solid than that of the testaceous, and much more so than the 
covering of the native Mollusca. Among the Romans, this designation was — 
signified by the terms of Crustata and Crustacea, the last of which forms the 
present name for the class. The earliest modern naturalists, like the more 
ancient writers, arranged the Crustacea between the fishes and the mollusca ; 
and Linneus placed them in his class Jnsecta, along with the apterous 
insects, including the spiders in the same class. Brisson was the first who 
formed them into a separate group. 
The Crustacea in one view ought certainly to occupy a more elevated 
place among the invertebral animals, than has been assigned to them, — 
above those, for instance, which are destitute of articulated members and 
eyes, and where the sexual organs are in the same individual; but, on the 
other hand, to place them between the Cephalopodous and Gasteropodous 
Mollusca, which would seem to be their place in the series, would break the 
chain of connection which unites this great class. It became necessary, 
therefore, either to place the Crustacea before moiluscous animals, or after 
them, and this last alternative has been adopted by modern zoologists. The 
Crustacea, besides the characters they have in common with the two follow- 
ing classes, possess some peculiar to themselves. They respire by bronchi, 
or by bronchial lamine generally annexed to their feet, or to their jaws. 
They have a distinct heart, provided with circulating vessels; feet to the 
