ON ANNELIDA. 
95 
years the systematic writers adopted this genus, such as it is 
in Gmelin, almost without making any other change than 
adding a very small number of species. This may be easily 
seen in Bruguieres’ “ Tableau des Vers,” in the Encyclope- 
dic Methodique, Blumenbach’s Manual of Natural History, 
that of the Baron Cuvier, the first edition of Invertebrated 
Animals, by M. de Lamarck, and even in M. Bose’s Treatise 
of Worms, although he indicates some new species. In the 
first mentioned work, however, we find a new established 
genus upon a species equally new, and the observation that 
the three sections of Linnoous and Gmelin should form so 
many distinct genera, when the mouth of the animals com- 
posing them should be better known. M. Oken also esta- 
blished a small section in this genus, but without any new 
observations. The naturalists of our country, in the mean 
time, and among others MM. Donovan and Leach, made 
known some species of Nereides not before observed. The 
nature of the labours of M. de Blainville also led him to 
endeavour to throw some light on this great genus, by care- 
fully studying the small number of species which he could 
procure. It was thus in considering the disposition or com- 
position of the appendages of these animals, that he was led 
to this result, of some importance to the philosophy of the 
science, that in the animals articulated externally, to which 
he has given the typical name of enlomozoaria, or entomozoa, 
each ring of the body in its complete state is provided with 
appendages, formed of three parts, one respiratory, or bran- 
chial, the other locomotive, and the third sensitive ; that all 
the rings are not necessarily provided with these parts of the 
appendage; that it may have three, two only, or one, or 
there may be none whatever in some of the lowest species, or 
in some parts of the body of an animal modified by some 
other cause. From this point the transition was easy to 
show how in the Nereides the general respiratory and loco- 
