IIIO General Notes, [November, 
stance which gradually becomes more opaque; sometimes the 
slit takes on the form of an equilateral triangle, and then the 
quantity of matter which exudes from itis greater; this matter 
obviously comes from the cylindrical tubes which are scattered 
in the glandular substance of the foot. A terminal plate having 
been formed the foot is withdrawn, and the plate and the byssus 
are merely connected by a delicate thread. The time necessary 
for an animal of average size to form the plate varies between 55 
and go seconds; in some cases two connecting threads become 
developed. The terminal plate, when studied under the micro- 
scope, was found to be formed of thousands of small granules, 
irregularly distributed, and varying considerably in size. The 
fine threads appear to be formed by the agglutination of granules 
of various sizes, but large granules are formed by the fusion of 
several smaller ones. : 
The formation of the byssus is regarded by the author as being 
very simple; the walls and the lamellæ of the byssus-cavity con- 
tinually secrete a byssogenous matter ; the lamellæ in the anterior 
and narrow part of the cavity unite and fuse with one another, 
while the narrow shape of the orifice gives the byssus-threads 
their form. Owing to the relations of the ventral groove of the 
foot each byssus-thread is immediately fused to the main trunk. 
The author doubts the correctness of A. Müller’s view that 
there is an agglutinating and a byssogenous substance; and 
speaks severely of the artificial character of that author’s classifi- 
cation of the species.— Fournal of the Royal Microscopical Society, 
August, 1885. 
