34 
The Presidenfs Address. 
wliicli has been used to receive them. The vexed question of 
the structure of the scales is fully considered^ particularly 
whether the wedge-shaped markings possess individuality as 
little scales^ or are mere inequalities on the surface of the 
membrane. The opinion of the author is that the markings 
are more or less elevations or corrugations on the surface, 
which answer the simple purpose of giving strength to a very 
delicate membrane. Seven slides illustrating the paper were 
presented as an addition to the Society^s collection of 
objects. 
7. A Description of a New Parasite in the Heart of the 
Edible Turtle/^ by Dr. A. Leared, was read May 14, and is 
pub. in '^Quar. Jour. Mic. Soc./ vol. ii, N. S., p. 168. 
This parasite, an undescribed species of Distoma, which the 
author provisionally names constrictum, was found in great 
numbers in the cavities of the heart of the turtle. The 
development and migrations of the Entozoa is a subject of 
great interest which has not received in this country the 
attention it deserves. 
The parasites met with by Dr. Leared were undoubtedly 
immature animals ; their larval condition and the situation 
where they were found, in the full current of the blood, 
suggest the idea that they were in the act of migrating, for 
we can hardly suppose the cavities of the heart to have been 
their permanent abode. If this conjecture be correct, it is 
the only instance (as far as I am aware) where the animals 
have been caught on their journey to the place where they 
were ultimately to be developed. 
8. A paper On the Generation of Acari in a Nitrate of 
Silver Bath,^' by R. L. Maddox, M.D., communicated by 
Mr. Shadbolt, was read May 14, pub. in ' Trans. Mic. Soc.,^ 
vol. X, N.S., p. 96. 
The facts narrated I think scarcely support the title. All 
that is clearly made out is, that the insects were found in 
considerable numbers on the surface of the solution. 
9. A second paper on the same subject, also communicated 
by Mr. Shadbolt, was read Nov. 11. In this it is stated 
that the insects were covered with a secretion which appeared 
to protect them from the action of the nitrate of silver. How 
the insects obtained admission under the circumstances 
mentioned is not easy to understand ; but remembering how 
extensively these little animals are diffused, and the difficulty 
of finding any situation entirely free from them, we can 
scarcely infer, in the absence of all evidence as to their origin, 
that they were propagated and developed in the solution on 
the surface of which they were found. 
