ON ANNELIDA. 
45 
Fabricius, we are indebted for a considerable number of ob- 
servations on the European species of nereis, as well as on 
many other animals of the Linnacan class of vermes. The 
first has proposed some changes in their distribution, intro- 
ducing an entire order, and at the same time a tolerable num- 
ber of genera. 
By him, however, the class vermes is still divided into but 
five orders, as he has united the last two of Linnaeus, 1. In- 
fusoria , for a numerous group of animals which he supposed 
were produced in vegetable or animal infusions, and his la- 
bours are all that we yet possess on this subject; 2. Helmin- 
t/iica, or worms, in which he ranges, in two distinct divisions, 
the intestinal worms, and the hirudo in one, and all the 
chetopoda, comprising among them the lumbrici, in the other; 
3. Mollusca, the same as Linnaeus, abstracting the chetopoda, 
but leaving the planarim, the fascioli and the medusa;, with 
the true naked mollusca; 4. Testacea ; 5. under the name of 
Cellularia, the lithophytes and zoophytes of Linnaeus; be- 
sides some very curious observations on the reproduction of 
the naides, and nereides, and the distinction of a great number 
of new species, science is indebted to this author for the esta- 
blishment of the genera Nais and Amphitrite, and the more 
exact circumspection of those previously established. His 
researches were subsequently made available by Linnaeus 
himself and several of his successors, in modifying the Sys- 
tema Natures. 
Though the celebrated naturalist, Blumenbach, has almost 
exclusively followed Linnaeus, in his methodical distribution 
of worms, he has nevertheless introduced an observation, as 
characteristic of the class, namely, that it never possesses 
articulated organs of motion, in opposition to what he had 
said concerning the insects, in which those organs are articu- 
lated ; “ a character,” he adds in a note, “ which appears to 
