76 
MODERN SYSTEM. 
Class I. CRUSTACEA. 
History. — “All the Crustacea, as their name imports, are covered by 
integuments composed of crustaccous materials, more earthy than 
those which envelope tire Myriapada, the Arachnvidea, and Insecta. The 
greater portion of these animals live on putrid or decomposing animal 
substances, and in all the sexes are distinct.” 
To the kindness and liberality of my much respected friend Dr. 
Leach, I am indebted for the above passage and following review (which 
he has since published in the eleventh volume of the Dictionnaire des Sci- 
ences Natnreucs) of the rise and progress of Crustacea; which is selected 
from his valuable manuscripts. 
“ The ancients were well acquainted with the Malacostraca (MctXot- 
xo<rrf%xoi), which they placed between the Moliusca and Fishes. Ari- 
stotle has dedicated a chapter to the species known to him ; Athenams 
has enumerated those used as food; and Hippocrates has made mention 
of such species as were considered to be useful in medicine. To the 
observations of Aristotle very little was added by Pliny ; and from his 
time until that of Rondolctius, Belon, Gcsner, Aldrovandus and John- 
son, (who likewise placed them between the Moliusca and Fishes ) lit- 
tle or nothing was done that tends in any way to illustrate their natural 
history or structure. Linjie, in the first (1735) and subsequent editions 
of his Systema Nulanv, placed all the Crustacea amongst the apterous 
insects, in the genera Monaculus, Cancer, and Oniscus. 
“ The Crmtaccfi were arranged by Drisson ( Regnum Animate) along 
with the Myriapoda and Arachmkka, being placed between the Fishes 
and Insects, under the Class Crustacea. 
“ Fabricius in his Systema Entomolagi<e (177 5) distributed these ani- 
mals into two Classes: 1 . Syngnatiia, comprehending Monoctdus and 
Oniscus, which he associated with Ephemera , P/iryganea , Tadura, Tcn- 
thredo, and other genuine Insects : 2. Agon ata, containing Cancer, Pa- 
gurus, Scyllurus,Aslacm, and Gammarus, to which he also added Scorpio. 
The same author in his Species (1731) and Mantissa Insectorum (1787) 
maintained the same general distribution; adding iu the former of those 
works the genus Squilla, and in the latter llippa, removing in each 
work the genus Scorpio from the Agomta. In the second volume of 
his Enlomotogiu Systematica (1793) his class Syngnutha contained only 
genuine Insects, the Onisci being removed to a new division named Mi- 
tosata, where they were associated with the Myriapoda; the rest he still 
placed with the Agonata, to which he added the genus Limnlus, Cymo- 
thoa and Galuthea. 
“ Latreille in his Precis des Caracteres des Inscctes (1796) (a work 
which commences a new sera in the science of Entomology, and in 
which, for the first time, the distribution of Insects into families is in- 
dicated), considered the Crustacea as forming three Classes or Orders 
