Hil: 
42 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. - 
the importance of the large number of observed facts he has gathered 
and very carefully recorded. 
In connection with Mr. Mackintosh’s paper, the observation may 
be allowed me (to which the author himself, I feel confident, would 
not make objection) that the circumstances affecting aérial waste are 
so variable in intensity that any calculations of time based upon 
such waste of boulder-pedestals must be accepted only as tentative 
of the solution of a problem which probably is incommensurable 
with our largest units of the divisions of time. 
Mr. A. J. Jukes-Browne, in his two papers, described instructive 
examples of some of the circumstances which affect the change of 
direction of river-courses; and Mr. Mellard Reade’s communication 
was a record of denudation and deposition, very instructive on 
account of the known average quantity of rainfall, and the known 
quantity of work done within a known time. 
On Petrology and Mineralogy, in addition to notes appended to 
stratigraphical papers to which allusions have been already made, 
the following communications were read, viz.:—‘ On the Basalt- 
glass (Tachylyte) of the Western Isles of Scotland,” by Prof. Judd 
and Mr. Cole; an ‘‘Additional Note on Boulders of Hornblende Picrite 
near the Western Coast of Anglesey,” by Prof. Bonney; a note on 
“‘Cone-in-Cone Structure,” by Mr. J. Young; and ‘‘ Petrological 
Notes on some North of England Dykes,” by Mr. J. J. H. Teall. 
Respecting the first of these papers I will merely say that it is, I 
believe, the most thorough and exhaustive account which has yet 
appeared of this interesting rock-substance ; and of the last I would 
venture the opinion that its subject is fully as exhaustively treated. 
The constancy of chemical composition and of intimate structure to 
which Mr. Teall called attention, strongly supports his opinion that 
the rock-masses constituting such dykes do not, as some have thought, 
consist, In any appreciable degree, of the fused substances of the 
sedimentary rocks through which they have been forced, but are 
wholly and directly of volcanic origin. 
Prof. Bonney’s instructive note on Picrite Boulders threw fresh 
light on a kind of rock but little known in this country, and respecting 
which, in conseyuence of its variability, some confusion of opinion 
had prevailed. 
Turning to Paleontology, not one Paleo-botanical paper was 
received. All the communications read during the Session referred 
to the Animal Kingdom, and of these, reversing the occurrence of 
last year, the majority related to Vertebrata. 
Of the papers on Invertebrata, that by Mr. R. F. Toutes "a On 
some new or imperfectly known Madreporaria from the Coral-rag 
and Portland Oolite of Wiltshire, Oxfordshire, Cambridgeshire, and 
Yorkshire,” which may be regarded as a continuation of former 
papers on the Corals of the Lias and Inferior Oolite, constitutes a 
valuable addition to our knowledge of the coral fauna of the Secon- 
dary rocks. ; 
Our acquaintance with Australian fossil Bryozoa was largely 
increased by a paper by Mr. A. W. Waters, who, by adding 18 new 
