310 SECTIONAL TRANSACTIONS.—C. 
of exploratory narrow-gauge borings at selected critical stations should 
prove both feasible and profitable in the course of such work. 
AFTERNOON. 
Excursion to Insch, Auchenbrodie, Den of Wraes and Wardhouse. 
Leader: Prof. H. H. Reap. 
Tuesday, September 11. 
Mr. K. P. OaKtey.—Pearl-like bodies in certain Silurian Polyzoa (10.0). 
Spheroidal bodies bearing a remarkable resemblance to minute pearls, 
on account of their opalescent lustre and fine concentrically laminated 
structure, occur in the zocecia of Ceramoporoid Polyzoa from the Wen- 
lockian beds of Cardiff, Dudley, etc. 
They were interpreted by Etheridge and Foord as chalcedonic infillings 
of mural-pores, and by Dr. Bassler as extraneous silicified ooliths. ‘Their 
true nature as internal calculi, probably formed during the lifetime of the 
polyzoa, was hinted at many years ago by Prof. Sollas. 
Detailed investigation has shown that these spheroliths are composed of 
calcium carbo-phosphate (dahllite) deposited from solution in thin concentric 
layers round nuclei. Their occurrence in the zoccial tubes, completely 
sealed in by the continuous diaphragms and unaccompanied by detrital 
material, makes it evident that they were formed in situ. Their restriction 
to the members of one or two closely related genéra is indicative of a control 
effected by the anomalous biochemical nature of the body-fluids of these 
particular forms. It is suggested that the spheroliths are analogous to 
urinary calculi, and that essential factors in their formation were practical 
absence of ‘ buffering ’ in the body-fluids and a substantial rise in their pH 
value during the degeneration of the polypides. ‘The conditions postulated 
have been reproduced experimentally and comparable results obtained. 
Dr. A. RatstricK.—The microspores of Carboniferous coals (10.25). 
By the use of solvents, the microspores of coal-forming plants have been 
extracted from coal in quantities sufficient to allow of statistical treatment. 
Over forty different varieties of microspore are recognised, and an attempt 
has been made to study their distribution through the coal seams of both 
lower and upper Carboniferous age, in Northumberland and Durham. 
Their use for the correlation of coal seams has been tested over a wide area 
and a large number of seams, with encouraging results. 
Several problems of theoretical interest, relating to the coal-measure 
floras, are suggested by this study. 
Mr. D. J. ScourrreLp.—The animal remains in the Rhynie Chert (11.0). 
So far, all the animal remains found in this Middle Old Red Sandstone 
chert belong, with one or two doubtful exceptions, to the Arthropoda, of 
which three classes are represented definitely, viz. Crustacea, Arachnida 
and Insecta, while the Myriapoda are doubtfully represented by a single 
specimen the true nature of which has still to be determined. ‘The single 
species Lepidocaris rhyniensis Scourfield represents the Crustacea, but is 
placed in a new order, viz. Lipostraca. ‘The Arachnids are represented by 
Protacarus crani Hirst, belonging to the order Acari; by a single specimen 
of Palzocteniza crassipes Hirst, thought to be one of the Aranez ; and by 
