^jTuraL.^ayrim'] PEOCEEDINGS OF SOCIETIES. 327 
with the two theories as to the nature of light, the phenomena of 
interference, differences between common and polarized light and 
polarizing apparatus generally. The paper was followed by a dis- 
cussion. 
Mr. Tatem furnished " Notes on a New Species of Mallomo7ias,'* 
differing from Mallomonos PlossUi in its much more elongated, almost 
naviculated form, proportionately shorter flagellum, much greater 
length of terminal hairs, and in uniformity of colour. He claimed 
for it the position of a new species, and proposed as its name, Mallo- 
monas elongatus. Its specific characters were detailed, and the creature 
itself exhibited. 
Mr. Tatem also brought for exhibition water containing vast num- 
bers of the free swimming young (about ytoo toVo iiich) of Vasicola 
ciliata (described and figured in No. 2 of the ' Montlaly Microscopical 
Journal '), but from which the adult free and invaginated forms had 
almost wholly disappeared. He stated that though the young Vasicola 
had been known to him for years, he had failed to recognize it as 
other than Megatriclia Integra, and suggested the possibility of its 
having been described by Perty (in this early stage of its existence) 
under that name. He also expressed his belief that Chcetomonas glo- 
bulus would ultimately be found to be a still younger form of Vasicola 
ciliata. 
Captain Lang exhibited slides illustrative of Mr. Collier's paper 
on polarized light ; amongst others, spiral crystals of sulphate of 
copper, Ballia hrunonis, and SjpJiacelaria filicina, the only two seaweeds 
he has found greatly affected by this method of illumination ; and the 
lips of a Fly, attached to which was a star-like hair from the ivy-leaf, 
which would not have been detected under ordinary light, but was 
distinctly apparent under the Polarizer. He drew attention to Mr. 
Swift's form of achromatic condenser, which, in a very simple and 
effective manner, gives a dark ground to polariscopic illumination, 
producing a beautiful effect. Later in the evening he exhibited the 
proboscis of the blow-fly, showing the salivary ducts and lancet-like 
ligula, with its sheath in situ, but lifted from the chitinous pleat of 
the membrane in which it lies. 
He also brought before the notice of the members Mr. Kent's 
cement, consisting of gum-damas dissolved in benzole, showing 
objects mounted in glycerine perfectly cemented and fixed by this 
material. 
Mr. H. A. Simonds also exhibited several polariscopic objects. 
April 20th, 1869. 
There was but a small attendance of members. 
Mr. Tatem contributed a paper " On Free-swimming Amorb^," in 
which he described the characters and habits of two species ; one of 
about T2V0 ToW 5 pi^ogressing with slow, oscillatory, and revolving 
motion ; the other of about to ^i^, having a flagellum, and swim- 
ming with slow, vacillating, and semi-rotatory motion. He also 
briefly discussed their relations to Amorbina generally. * 
* Keport suppUed by Mr. B. J. Austin. 
