RANK OF GROUPS EXEMPLIFIED. o71 
and lives only in such situations. Now, if this aquatic 
division of the sub-genus Parus, instead of merely 
containing this one bird, comprised twenty or thirty 
species, we have every reason to conclude, judging from 
analogy, that it would of itself form a little circle ; and 
would, consequently, contain a new set of represent- 
ations of the usual types. But this, as we have 
already remarked, does not occur in the class of birds ; 
although it may possibly be found among insects. We 
therefore terminate our series of circles with the sub- 
genus Parus proper ; and thus get the following scale 
of rank in the groups we have progressively passed 
through. As the same results would attend our search 
after the station of the common swallow-tailed butterfly 
(Podalirius Machaon Sw.), we shall give the results of 
both enquiries together — the number being th7ee times 
three. 
PARUS BIARMICUS, PopALirRius Macnaon. 
1. Kingdom. Animalia. 1. Kingdom. Animalia. 
_ 2. Sub-kingdom. Vertebrata. 2. Sub-kingdom. Annulosa. 
3. Class. Aves. 3. Class. Ptilota. 
4. Order. Insessores. 4. Order. Lepidoptera. 
5. Tribe. Dentirostres. 5. Tribe. Diurnes. 
6. Family. Sylviade. 6. Family. Papilionide. 
7. Sub-family. Pariane. 7. Sub-family. Papilione. 
8. Genus. Parus. 8. Genus. Papilio. 
9. Sub-genus. Parus proper. 9. Sub-genus. Podalirius. 
(331.) There are several deductions of the highest 
importance to be made from this table, but at present 
we must view it only with reference to the value of the 
groups in the first columns. That these, and these 
only, so far as the bird in question is concerned, are 
natural, is to be inferred from the fact that they are 
each circular groups, already demonstrated as such by 
rigorous analysis.* ach circle, according to its supe- 
rior rank, embraces all those that are beneath it; the test 
or proofs of the accuracy of each reposing on precisely 
the same principles. We traverse, in fact, eight circles, 
one within the other, before we arrive at that which 
brings us directly to the bird before us. It would, no 
* Northern Zoology, vol. ii. p. 200, &c. 
