70 ' Improvements in Physical Science in 1815. (Jan. 
that when the heart of a carp was laid open, it ceased to beat much 
sooner if the fish was allowed to swim in water than if it was kept 
guiet in the air. 
5. From the discovery of Mr. Rose that urine in hepatitis con- 
tains no urea, I think it may be inferred that one use of the liver, 
if not the only one, is to separate urea from the blood; so that it 
would seem to be the principal organ concerned in the formation of 
urine. 
XI. ZOOLOGY.* 
The division of animals into four types has been carefully 
examined and discussed by several learned zoologists, who are 
much divided in their opinion as to the correctness of this distri- 
bution, which was proposed a few years since by M. G, Cuvier. 
That the vertebrous, molluscous, and annulose animals form three 
great and natural groups, is certain ; and it is probable that the 
radiated animals form another. The questions to be decided are: | 
Where are we to place the amprey and mysxine, animals having no 
vertebra or jaws; but agreeing with the vertebrosa in most other 
points? And where the cirrhipedes, whose structure is partly. that 
of the mollusca and partly of the annulosa? Dr. Blainville con- 
ceives that the cirrhipedes offer no obstacle to this distribution, and 
that they form what he calls a subtype, intermediate between the 
moliusca and annulosa; and Dr. Leach entertains the same opinion. 
Many of the French zoologists still maintain Lamark’s division of 
animals into those with and into those without vertebre. 
Le Sueur, Desmarets, and Savigny have discovered that the 
animals of the genus pyrosama, of some alcyonia,> and flustre, are . 
genuine mollusca, and not zoophytes. M. Savigny names these | 
animals ascidées composées; and he has written a monograph on 
them, which was read to the Institute of France. 
Dr Leach has published a general classification of the animals 
named by Linné insecia, which he considers as forming one group, 
and the vermes another of the type annulosa. In the dissertation 
which is published in the last number of the Linnzan Transactions, 
these animals are considered as forming four classes: viz. 1. Crus- 
tacea: 2. Myriapoda: 3. Arachnides: 4. Insecta. ‘The myri- 
apoda were considered by Latreille as belonging to the arachnides ; 
but they were published as a distinct class by Dr. Leach, in the 
seventh volume of the Edinburgh Encyclopedia, three years ago. 
M. Savigny has discovered that mandibles and maxille exist in 
the lepidopterous and hemipterous insects, although in a modified 
form. And Sir J. Banks observed, that the palpi of spiders were 
in fact legs: this was also noticed by Dr. Blainville about the same 
time, and he has proposed a division founded on the number of the 
legs of this group. 
a 
* For the account of the improvements in this branch of science the editor is 
indebted to a friend. 
+ Lhe animals of aleyonium digitatum are true zoophytes. 
