24 6 Proceedings of the 



whence derived has not been noticed ; the purport of this paper is to sup- 

 ply that omission. Until Good Friday last I had not seen any of this 

 marl. As this day is always a customs holiday, and is not kept as a holy 

 day in the north, I took a walk as far as Witnean, a little more than 

 seven miles from this place, to look at the deposit there. On taking up 

 some marl which had been laid on the bank of the loch, I fancied, from 

 its peculiar character, that I knew the source of the supply of silex, at 

 least the greater part of it. On my return in the evening, I placed a 

 very small quantity of the marl on a slip of glass and saturated it with 

 water ; then laid another piece of glass on this, and transferred the whole 

 to my microscope, and was delighted to find, as I had suspected, that dia- 

 tomacese, those lovely siliceous, but somewhat doubtful vegetable forms, 

 were abundant in it. I forwarded some to London ; this was handed to 

 Professor Smith of Queen's College, Cork, the author of the standard 

 work on Diatomacese. He kindly examined it, and sent me a prepared 

 slip, with a list of those found by him in. the first examination, showing 

 forty-three species belonging to twenty genera, and added, &c, &c. As 

 well as these, there were a great number of spiculse of the fresh-water 

 sponge (Spongia fluviatilis of Johnston). He, however, met with no new 

 forms. Professor Arnott of Glasgow has also examined some, and finds 

 diatomacese abundant. Christopher Johnson, Esq. of Lancaster has de- 

 voted a good deal of attention to it, and says that he has found at least one 

 new and undescribed ; and we may reasonably hope that when the " &c. 

 &es.," are worked up, the list will be greatly extended. There is" ano- 

 ther deep deposit at Brakegoe, near Thrumster, five miles from this place, 

 which also abounds in similar forms, but not quite in such abundance. 

 As well as these two lochs, marl is met with in various parts of the county. 

 From some of these deposits I have obtained small parcels ; they are com- 

 paratively bare of diatomacese. I wish to speak cautiously here. From 

 not having collected the marl myself, I may not have been furnished with 

 good samples. Should I ever have the pleasure of visiting these localities, 

 I hope to give all a careful examination. As I intend this more as a me- 

 dium of introducing the marl to the notice of microscopists, and to request 

 the distribution of it amongst our members, than as an essay on diato- 

 maceae, I trust that it will be accepted as such ; and I hope that they will 

 feel as much pleasure in the examination as I have. I could willingly 

 dwell on many interesting particulars and facts connected with the extent 

 and depth of these deposits' — the manner of using the marl — the good 

 effected by the proper use of it, as shown by the thousands of acres of 

 land brought into cultivation and benefited, and, per contra, the great 

 injury caused by injudicious application — and then of the animal and ve- 

 getable matter of which it is composed — showing the infancy, youth, and 

 beauty — perfection, age, and decay — of the millions upon millions of or- 

 ganized objects which have lived and died, and whose remains are buried 

 in these lochs — and then the lengthened periods that must have passed 



