368 Proceedings of Societies. 



whole, one of the most interesting localities in the island ; and a careful 

 examination of them would form a valuable contribution to Scottish geo- 

 logy. The district lies far out of the ordinary track of the tourist, and 

 the accommodation, where it can be had, is not of the best: but these 

 disadvantages would doubtless be more than compensated by a ramble 

 among the beautiful sections which abound in the creeks and caves of that 

 solitary shore. 



4. On some Worm Tracks in Silurian Slates. By Alex. Bryson, Esq. 



Mr Bryson showed that considerable difficulty was felt in accounting 

 f jr these curious appearances on the Silurian slates at Thornielee, Peebles- 

 shire. They had been named by Professor M'Coy Crossopodia Scotica, 

 or fringed-footed animals. Sir Roderick Murchison described them as 

 occurring of considerable length, even extending to yards. Mr Bryson 

 was of opinion that the length was merely due to a track made by a worm 

 of about six inches long, in mud of a rather crisp than slimy condition ; 

 and that the different appearances presented by the track, as compared 

 with the surrounding matter, was due, not to the remains of the worm, 

 but to dry dust blown into the track by the wind, on the recession of the 

 ocean, which formed the lowest Silurian beds of Scotland. On the tracks 

 found by Mr Bryson in the Llandeilo flags of Wales, he observed that 

 many naturalists had mistaken for setae merely the effects caused by 

 wind blowing light sand over tracks made by gasteropodous molluscs ; 

 and stated, that tracks which he found at Port Rheudyn, in Wales, in 

 almost the lowest beds of the Silurian slates, were quite identical with 

 those he saw in the act of formation by the common Turbo littoreus, on 

 the sands of Tremadock, a few miles south of Port Rheudyn. Mr Bryson 

 exhibited some very large slabs, showing numbers of these tracks, sent 

 him by the kindness of Mr Chaffers, the lessee of the quarry at Port 

 Rheudyn, Wales. 



January 24, 1855. Dr Lowe in the Chair. 



1. On the Discovery of Diatomacece in the Silurian Slates of Scotland. 

 By Alexander Bryson, Esq. 



In a former paper, read at the last meeting of the Society, Mr Bryson 

 had indicated a hope that Diatoms might be found iu the lower Silurian 

 formations of Scotland, from the peculiar appearance resembling or- 

 ganisms which he observed in a microscopic section of the slate from 

 Thornielee Quarry, in Peeblesshire. One form is identical with a rare 

 species found in the guano of Ichaboe, both in form and colour. In an 

 endeavour to separate the alumina from the silica in the slate he had met 

 with difficulties, as any solvent of alumina also acted on the silica of 

 which he supposed the diatoms to consist. Dr George Wilson suggested 

 the boiling of the powdered slate in Nordhausen sulphuric acid, which was 

 found after a long time to isolate the silica. After many washings of the 

 residue with distilled water, the author found several forms of diatoma- 

 ceas, two identical with living species, and four or five quite aberrant. 

 After digestion with nitric acid the organisms seemed fewer, which he 

 referred to their being more horny than silicious. 



2. Notes on a Species of Nostoc or Shy-Jelly (specimen exhibited by 

 Dr Heddle). By Alexander Bryson, Esq. 



3. Description of a New Species of Trematode Worm, with Observations 

 on the Structure of Cercarice. By T. Spencer Cobbold, M.D. 



Specimens of the worm were exhibited. They had been obtained from 



