TRANSACTIONS OF THE SECTIONS, 99 



Lightbody of Ludlow in the upper Ludlow shales on the banks of the river Tame. 

 The addition of a new crustacean to the upper Silurian list of organic remains is an 

 interesting fact, and the fossil was new to Mr. Salter. The various crustaceous 

 remains lately discovered in the upper Ludlow shales and tilestones are assuming 

 an important feature in geology, and Mr. Symonds quoted the supposed " Cephalas- 

 pides '' in the tilestones of Kington, discovered by Mr. Banks, and expressed his 

 doubt whether, after all, the " Cephalaspidean " plates would not turn out to be 

 those of crustaceans. A drawing of this fossil by Mrs. H. Salwey of Ludlow has 

 been engraved on plate for the Edinburgh New Philosophical Journal, Oct. 1855. 



On the Fauna of the Lower Silurians of the South of Scotland. 

 By Professor Wyville Thomson, F.R.S.E., Belfast. 



Exhibition of a Series of Preparations obtained from the Decomposition of 

 Cannel Coal and the Torbane Hill Coal. By Dr. Tryfe. 



On the Probable Maximum Depth of the Ocean. 

 By Searles V. Wood, Jun. 



The author, after pointing out that if a surface be rugose in such a manner that 

 for every elevation upon it there exists an equal depression, and that if the interstices 

 be then filled in with liquid, it would be found, that when the area left uncovered 

 equalled the area covered by the liquid, the height of the prominences above the 

 hquid level would equal the depth of the depressions beneath the same level, and that 

 when such areas were as 2 to 1, or 3 to 1, the heights and depths would be in those 

 ratios, and so on in direct proportion, — suggested that if it were assumed that the 

 earth's surface if uncovered would exhibit such a rugosity as above, then, since the 

 ocean area is to the land area as 3 to 1 (nearly), it would be found over large spaces 

 of a depth three times the average height of any mountain mass ; and that if the 

 average height of the mountain mass of the Himaleh were taken at from 13,000 to 

 14,000 feet, a lurge space of the ocean would give soundings of from 39,000 to 

 42,000 feet (eight miles), being three times that height. 



BOTANY AND ZOOLOGY including PHYSIOLOGY. 



Botany. 



An attempt to classify the Flowering Plants and Ferns of Great Britain 

 according to their geognostic relations*. By John G. Baker. 

 L Fundamental Generalities. — 1. In regulating the distribution of species, and 

 modifying specific types, the subjacent geological formations, principally by reason 

 of their mechanical properties, exercise an influence, which, taken as a whole, is 

 secondary only to that of climate, which it modifies, and by which it is modified 

 perpetually. 



2. With reference to the facility with which they yield to disintegration and to 

 their hygroscopicity and porosity, strata are essentially separable into two principal 

 classes, dysgeogenous and eugeogenous. 



3. Dysgeogenous formations are those which are disintegrated with difficulty and 

 yield only a feeble detritus. On a grand scale they absorb moisture readily, and 

 furnish stations characterized by their comparative dryness. Rocks of this class 

 mostly contain a large proportion of carbonate of lime in their composition. 



4. Eugeogenous formations are those which abrade easily and yield an abundant 



* This paper, with a complete catalogue, &c., has been issued in the form of a pamphlet, 

 and may be procured of the author, Thirsk, Yorkshue, or of the pubUshers, W. and F. G. 

 Cash, London. 



7* 



