THE ANNALS 
MAGAZINE OF NATURAL HISTORY. 
(THIRD SERIES.] 
No. 32. AUGUST 1860. 
XIV.—On Recurrent Animal Form, and its Significance in Syste- 
matie Zoology. By Curusert Cotiinewoopo, M.B., F.L.S., 
* 
No one conversant with Zoology can have failed to remark the 
fact of the recurrence of similar forms in different groups of the 
animal series. Not only do species of one family resemble species 
of an allied family, but group with group, order with order, and 
even class with class, and subkingdom with subkingdom, can pro- 
duce instances of the most striking homomorphism. The resem- 
blances to which I allude are those of external form, unaccom- 
panied by homologies of internal structure; nevertheless I 
imagine that this peculiarity, instead of entirely destroying its 
interest, and rendering it valueless, as some have appeared to 
consider, only places the subject in a different category of scien- 
tific facts, and invests it with a value peculiar to itself. In the 
history of classification it has always naturally happened that ex- 
ternal form, rather than internal structure, has been the main- 
spring of systems; the knowledge of structural homologies has 
been painfully accumulated, and the systems built upon the 
characters presented by external form have from time to time 
been corrected by increasing knowledge of structure, till in 
these days zoologists have agreed that structure, and not form, 
should be the basis upon which systems should be framed with 
the greatest claim to accordance with Nature. Nevertheless 
systems founded upon homologies are liable to be interfered with, 
and their symmetry affected by encroachments of form; so that 
eminent zoologists differ as to the position of animals, even in the 
present advanced state of zoology, owing to the fact that, while 
one regards homologies of structure as paramount, another allows 
* Communicated by the Author, having been read before the British 
Association at its Meeting at Oxford (1860). 
Ann, & Mag, N. Hist. Ser.3. Vol. vi. 6 
