730 Proceedings of Royal Society of Edinburgh. [sess. 
rock oysters, although usually known under several different names, 
are now by most conchologists admitted to he only localised 
varieties of one and the same species, Ostrea glomerata.” The best 
oysters are obtained from the shallowest beds, and the very best 
are dry at low water. The mud oyster of New Zealand, as well 
as of Australia, is 0. edulis, Linn., var. purpurea , Hanley; 0. 
chiloensis, Sowerby, is identical with the small form known as the 
“native” in the London market. I am informed by Sir James 
Hector of New Zealand, that the common name of mud oyster 
given in Hutton’s Manual is misleading, and ought rather to be 
the deep-water oyster of New Zealand, since it is found in from 
3 to 12 fathoms of water, and usually on a shelly bottom. 
Movements of the Oyster as a whole . — A specimen of the oyster 
laid out in pure salt water, with the gills fully expanded in front 
and posteriorly, was found to have moved to the left at the 
posterior end 1 inch in 8 J. hours; while the hooded head, or 
anterior end, remained relatively fixed, as it is too shut in to 
allow the free play of the cilia. After a time the gills were drawn 
.in, and the whole animal shrunk considerably. 
Labial Palps . — The labial palps are a pair of roughly triangular 
or fan-shaped bodies of a pale flesh colour lying on each side of 
the mouth ; the inner and outer on each side passing respectively 
into the lower and upper lips. When detached its shape is often 
lost completely. The line of attachment to the body is somewhat 
inclined to its long axis, and is just a continuation to the angle of 
the mouth of the line of attachment of the gills. 
Of the palps together, the left was comparatively inactive, 
whilst the right exhibited considerable activity. The outer 
rotated right-handed, taking 42 J minutes for the first round, and 
an average of 23 minutes for the whole, and 3 minutes for the 
quickest round. The inner began to rotate right-handed very 
slowly. It then reversed its direction of rotation several times, 
always moving very slowly. The left inner palp rotated right- 
handed, and gradually left the outer palp, which was stationary. 
The first round took 36 minutes, after which the motion was very 
slow indeed, and was not recorded. The two inner palps together 
with left uppermost gave evidence of very slight left-handed rota- 
tion. Of the right palps, the inner rotates left-handed pretty 
