440 PROCEEDINGS OF SOCIETIES. 



New form of Cophsphcerium, inhaliting intercellular spaces of 

 a fiowering plant, shoion. — Mr. Archer exhibited a preparation 

 by Professor Alexander Dickson of the leaves of a warm-house 

 plant, containing in the spaces examples of a phycochromaceous 

 alga, morphologically, if the term be allowable, falling under 

 Nageli's genus Coelosphserium. It seemed to differ from the 

 ordinary pond species in the reddish-brown colour of the colonies, 

 and in the elongate, not orbicular cells these seemingly seated in 

 a proper cup-like, gelatinous support — the two together some- 

 what like an acorn in its cup — this cup-like base sometimes 

 appearing as if somewhat prolonged downwards, but not in so 

 pronounced a manner as may sometimes be seen in the allied 

 form, met with in ])Oo\fi, Go mphosplicsriaaponina, Kiitz. Altogether 

 the form would appear to be heretofore undetected — probably its 

 unusual habitat may have something to say to that — instances of 

 similar allied forms occurring in the tissues of flowering plants 

 are, however, now not rare. If one should meet the present 

 form in a pond it would at once strike the eye as unusual. 

 Mr. Archer thought he might be justified in calling this alga 

 Goelosphcerium Dicksoni, after its discoverer. 



Section of Spine of Phyllacantlms imperialis,s'hown. — Mr. Mack- 

 intosh showed a cross-section of the spine of Ph-yllacanthus 

 imperialis, Lam., taken near the apex. It presented a very 

 regularly stellate appearance, due to the projection of a number 

 of ridges on the surface, and had a very thick external crust. 



Crystals of Mngnesian Pliospliatefrom Urine, of unusually large 

 size, shown. — Dr. Tichborne showed crystals of ammoniacal 

 magnesian phosphate from urine, of remarkably large size, being 

 the largest he had ever seen naturally deposited ; some of them 

 were 6 mm., and, being of a beautiful regularity, were particularly 

 suitable for polarisation. 



16th Jamiary, 1879. 



Section of Syenite, with imbedded slender pristns, considered to he 

 disthene, shoion. — Professor Hull, F.R.S., exhibited a thin section 

 of a syenite (quartz, felspar, hornblende) from Slieve Gullion, 

 containing long prisms of a greenish glistering mineral, considered 

 to be disthene (kyanite), the analysis of which gives silica 36'8, 

 alumina 63"2 (Dana). This mineral was formerly discovered by 

 Professor E. S. Scott, in Donegal. "With a magnifying power of 

 about 225 diameters the grains of silica were seen to contain 

 numerous fluid cells, together with long prisms abruptly truncated. 

 Some of these prisms were also continued into the felspar, and, in 

 comparison to their diameters, were of great length and perfectly 

 straight. Though generally colourless, they sometimes presented 

 shades of brown or umber. The mineral polarises vividly, and is 

 supposed to be disthene. Olivine is also present. 



Cutis vera from Heel, stripped of Epithelium, shown. — Mr. B. 

 Wills Eichardson exhibited two blue-stained sections, each an inch 



