124. British Association. 
‘“‘ On a new genus of Mollusca Nudibranchiata.” By Messrs. Alder 
and Hancock. | 
‘This new genus is founded on the Tritonia arborescens of authors 
and its allies, which are distinguished from the true Tritonie (T. Hom- 
bergii, &c.) by the form of their tentacula, and the free, arborescent 
nature of their branchi. hese characters alone induced the authors 
to consider them generically distinct before they had an opportunity 
of examining their internal structure, in which such important dif- 
ferences in the digestive organs were exhibited as to show that this 
new genus, for which the name of Dendronotus is proposed, should 
be removed from the family Doride to that of Holide, to be placed 
first in order, as the connecting link between these two families. 
“« On the Cilia and Ciliary Currents of the Oyster.” By the Rev. 
J. B. Reade. 
The author stated that in a microscopic investigation of infusoria 
which had for some years occupied his attention, he had been led 
particularly to notice the beautiful contrivance by which many spe- 
cies, when not exerting their powers of locomotion, are supplied with 
food. When they are examined under the microscope by such an 
arrangement of transmitted light as makes the infusoria luminous 
points on a perfectly dark field, it is immediately seen that the action 
of the cilia attached to their tentacula produces a strong current in 
the water, and hereby a countless number of minute living organisms 
is brought within the influence of the cilia, and a sufficient supply is 
selected for food. ‘Thus with respect to infusoria it is a known fact, 
that the absence of the prehensile organs possessed by larger crea- 
tures is compensated by this delicate but efficient ciliary apparatus. 
It is also a fact equally well known, that the lips of the oyster which 
surround the orifice of the alimentary canal are in the same manner 
fringed with cilia; and that these cilia of the oyster, as of infusoria, 
equally cause currents in the water. But it has never been suggested 
and proved by any naturalist, that the proper office of the cilia of 
oysters is to bring to these acephalous mollusks that food which they 
have no power to follow or to seize. Such however, without doubt, 
is the case ; and accordingly an examination of the contents of the 
stomachs of oysters discovers to us their infusorial food ; and after 
undergoing the process of digestion in the stomach, the siliceous 
shields of these infusoria, deprived of their organic and carbonaceous 
integuments, are ejected as effete matter. In a paper communicated 
last year to the Microscopical Society of London, on animals of the 
chalk still found in a living state in the stomachs of oysters, these 
infusoria were described and enumerated. The apparent identity ex- 
isting between these recent living infusoria and the fossil makes the 
inquiry of considerable interest to the geologist; for the addition of 
this connecting link to the chain of organized beings extends a con- 
tinuous line of the same organic structure from the secondary for- 
mation to the tertiary, and seems to preclude the supposition of 
Prof. Phillips, that below the tertiary formation are no recent species. 
Whether or not this conclusion be admitted, it is a fact, ascertained 
by pursuing this inquiry, that the oysters and other bivalves, which are 
