DR. A. FARRE ON THE STRUCTURE OF THE CILIOBRACHIATE POLYPI. 391 
may be easily constructed of every variety of depth), these should be filled with sea 
water, and a specimen of the species to be examined placed in each, care being- taken 
to adapt the depth (from side to side) of the trough to the thickness of the specimen, 
it being very desirable that no more water should intervene between the latter and 
the sides of the glass than is just sufficient for the purpose. 
If the specimens are tolerably recent it will seldom fail that in a short time the 
animals, which always contract the instant that they are disturbed, will begin to ex- 
pand themselves, in which state many may be observed by the naked eye, and a very 
cursory glance under the instrument will then show which are the best adapted for 
observation. 
For this purpose it is necessary that a clear reflected light should be transmitted 
through the object, care being taken to avoid all artificial light, which is totally in- 
adequate to supply that delicate and perfect definition requisite for the examination 
of objects so extremely minute as those which form the subject of the present essay. 
This method, which if rigidly pursued, greatly limits the time during which the in- 
vestigation may be continued, is yet the only one that can be safely trusted to ; and 
for subjects of this nature I have therefore long ceased to use any other than a clear 
daylight*. 
The figures which are added in illustration were drawn from the specimens by 
being previously outlined by the aid of a camera lucida attached to a reserve eye- 
piece, to allow of its being instantly substituted whenever a favourable specimen 
should present. By this means a faithful record of appearances is preserved that 
cannot be equalled, and indeed hardly obtained by other means, although it is 
scarcely in the power of a drawing to convey an adequate idea of the exquisite^ 
beauty of the living objects. 
PLATE XX. and XXI. 
Bowerbankia densa^f, Mihi. 
Fig. 1. Found commonly on Flustra foliacea, thickly aggregated in masses of 
half of an inch to one inch diameter. 
* The very perfect instrument, in the possession of my brother, with which I have been enabled to make 
these observations, was constructed by Mr. Ross, of London, to whom the greatest credit is due for the perfec- 
tion to which he has brought his glasses. 
+ This I believe to be either entirely new, or to have been confounded with the Grape coralline of Ellis, 
(Corall. pi. xv. f. 25. c. C. D.) the Valkeria uva of Fleming (Brit. Anim., p. 551. gen. lxx. 197.), &c. What- 
ever be the animal meant by Ellis, it certainly differs materially from the present species, which I cannot refer 
to any described genus with which I am acquainted. Believing it to be new I have named it after my friend 
Mr. Bowerbank, whose zeal displayed on this as on many other occasions where the study of natural history 
may be promoted, was mainly instrumental in inducing me to follow up these investigations, on account of the 
many supplies that I received from him, and I gladly therefore take the opportunity of acknowledging and re- 
cording the obligation that I am under to him. 
