28 
Busk on Avicvlaria. 
Their structure so obviously indicates their aptitude for pre- 
hension, that the supposition of such being their function has 
been long entertained : and 1 have myself no doubt whatever 
as to its being so ; for, as Dr. Johnston observes, " although 
they are too short to hand the prey to the mouth, yet, retained 
in a certain position, and enfeebled or killed by the grasp, the 
currents set in motion by the ciliated tentacula may then 
carry it within reach." (' Brit. Zooph.' p. 334.) Some time 
in the last year, a specimen of Scrupocellaria scruposa, if 
I remember right, was exhibited at one of our meetings, with 
a minute vermicule, retained in the grasp of its avicularia ; and 
the same thing seems to have been repeatedly noticed. An 
instance of the kind occurred to me when at the sea-side this 
autumn, and I have made a figure to represent the occurrence 
(Plate II. fig. 12). It is of a portion oi Scrupocellaria scruposa, 
two of the avicularia on which have, apparently simulta- 
neously, caught a minute vermicule which they retained with 
a most tenacious grasp. I kept the zoophyte under observa- 
tion for several days, in the living state, and during that time, 
in fact, till the whole died, the grasp of these organs was not 
relaxed ; and, although the movements of the captive were 
very active and apparently energetic, it was unable to liberate 
itself from the grim hold of its tiny but persevering antagonist. 
Another instance of the grasping propensity of these organs 
is exhibited in fig. 10, where two of them appear to be 
engaged in deadly combat. This figure is also intended 
to show the disposition of the muscles when thus employed. 
Considering, therefore, the conformation of the avicularia, 
and the instances in which objects of prey of different kinds 
have been noticed engaged by them, I think it is impossible 
to avoid the conclusion that they are for the prehension of ob- 
jects, either for the purpose of using them for food when dead 
and powerless, as suggested by Dr. Johnston ; or it may be for 
purposes of defence. 
With respect to the structure of the avicularium, I have 
already stated what is known ; and have, in addition, only 
to remark that it has occurred to me to notice a circumstance 
hitherto overlooked, and which may eventually serve to throw 
some light upon the " peculiar body " contained in the cell to 
which I adverted in my observations on Notamia. It was in 
(' Ann. Nat. Hist.,' 2nd Ser., vol. v. p. 198), than has hitherto been given 
to it. And with regard to this, it should be borne in mind, though per- 
haps the character is of no great importance, that all the Brachiopoda 
have striped muscular fibres, whilst for the most part the other classes of 
Mollusca, with some exceptions — Pecten, for instance — all have muscles of 
the unstriped kind. 
