Proceedings of Societies. 207 
i>arh of the four classes of Vertebrata ; and lias communicated in tlu's paper a de- 
tailed account of his observations, arranged according as they relate to structures 
more and more complex. In a former paper, published in the Philosophical 
Transactions for 1833, the lens of the Cod fish was taken as the type of the 
simplest of these structures, in as much as all the fibres of which it is compos- 
ed converge, like the meridians of a globe, to two opposite points, or poles, of 
a spheroid or lenticular solid ; both of which poles are situated in the axis of 
vision. The structure which ranks next in respect of simplicity is that exhibit- 
ed in the Salmon, among fishes ; in the Gecko, among reptiles ; and in the Hare, 
among Mammalia. It presents at each pole two septa placed in one continuous 
line, in different points of which all the fibres proceeding from the one surface 
to the other have their origin and termination. A structure somewhat more 
complex is met with in the lenses of most of the Mammalia, and is particularly 
exemplified in the lion, the tiger, the horse, and the ox. Three septa occur at 
each pole in the form of diverging lines inclined to one another at angles of 120. 
The next degree of complexity is presented in the lens of the whale, the seal, 
and the bear, which contain, instead of three, four septa on each side, placed at 
right angles to each other in the form of a cross. In some specimens of lenses 
of whales and seals the author observed two septa from each pole, forming one 
continuous line, from each of the extremities of which proceeded two others 
which were at right angles relatively to one another : so that there were 
in all five on each surface. The most complex structure is that of the lens of 
the elephant, which exhibits three primary septa diverging at equal angles from 
the pole, and at their extremities bifurcating into two additional septa, which 
are inclined to each other at angles of 60, these latter being the real septa, to 
which the fibrous radiations are principally related. In some lenses of the ele- 
phant the author found the three septa immediately proceeding from the poles 
exceedingly short, and approaching to evanescence ; so that he has no doubt that 
occasionally they may be found to have disappeared, and that the other six septa 
will then all diverge from the poles, like the radii of a hexagon, at angles of 60. 
February 4th " Memoir on the Metamorphoses in the Macroura, or long- 
tailed Crustacea, exemplified in the Prawn (Palaemon serratus.) By John V. 
Thompson, Esq., F. L. S., Deputy Inspector- General of Hospitals. Communi- 
cated by Sir James Macgrigor, M. D., F. R. S., &c. 
" The author gives descriptions, illustrated by outline figures, of three differ- 
ent stages of growth of the Prawn ; the first being that of the larva, immediate- 
ly on its exclusion from the egg ; the second, at a later period, when it has ac- 
quired an additional pair of cleft members, and a pair of scales on each side of 
the tail ; and the third, at a still more advanced stage of developement, when it 
presents the general appearance of the adult Prawn, but still retains the nata- 
tory division of the members, now increased to six pair. The author thinks it 
probable that an intermediate stage of metamorphosis exists between the two 
last of these observed conditions of the animal." Zone?, and Edin. Phil. Mag. 
MEDICO-BOTANICAL SOCIETY, April 27, 1836 W. T. IlifF, Esq. in the Chair. 
Mr IlifF presented specimens of the Ilex Paraguayansis, or Paraguay tea. The 
Ilex, according to the description given of it, is about the size of an orange tree, 
and has opposite, .shining, oblong, serrated leaves. The flowers are in axillary 
umbels, and have four petals, and four stamens. The leaves, which are gather- 
ed for tea, are taken from plants of two or three years of age, or when the trunk 
is about an inch in diameter ; they are very fragile when dry, and M. Virey says 
