ANNIVERSARY ADDRESS OF THE PRESIDENT. xHx 



Trilobites, closely allied to some of the forms already known in the 

 lowest fossiliferous beds of America. To these fossils Mr. Salter has 

 given the name of Palceopyge Ramsayi. Mr. Salter then proceeds 

 to describe the other beds in the series which underlie the fossilife- 

 rous beds, consisting of shales and sandstones, in some of the lowest 

 of which are beds of .conglomerate of considerable thickness (one 

 is 120 feet thick). These conglomerates are chiefly composed of 

 quartz, and indicate the proximity of older and perhaps volcanic 

 lands. 



The discovery of these traces of organic life in these old rocks, how- 

 ever interesting in a palseontological point of view, does not justify us 

 in looking on them as representing a new system or group. They do 

 not indicate the existence of new or unknown forms, and can there- 

 fore only .be considered as a further extension downwards of the 

 Lower Silurian formation of Sir R. Murchison. They appear to 

 point, however, more directly to the very commencement of organic 

 life, which reached a considerable development in the succeeding 

 strata, whatever may have been the lapse of time occupied in their 

 gradual deposition. It is unfortunate that they are not in a more 

 perfect state of preservation, since, although there can be no doubt of 

 their organic origin, they are in far too imperfect a condition to per- 

 mit any exact conclusion as to their true affinities and connexions. 



An interesting communication has also been recently read at one 

 of our Evening Meetings, from Sir R. Murchison, " On the discovery 

 of Upper Silurian rocks and fossils near Lesmahago, in the south 

 of Scotland, by Mr. Robert Slimon." This discovery is the more 

 important, as, notwithstanding the extensive development of the 

 Lower Silurian rocks in the S.W. parts of Scotland and in Ayrshire, 

 the existence of these upper beds was previously unknown in Scot- 

 land. The descending order of the strata is well seen on the banics 

 of the Nethaw River, Logan Water, and other tributaries of the 

 Clyde. Here the lower carboniferous rocks, in which the coal-field 

 of Lesmahago occurs, are underlaid by the Old Red Sandstone for- 

 mation, which is well exposed between Lanark and Lesmahago. 

 Towards its base the Old Red is here marked by a powerful band of 

 pebbly conglomerate, while the base itself is made up of alternating 

 red and light greenish grey flagstones and schists. These are again 

 underlaid by dark grey, slightly micaceous, flag-like schists contain- 

 ing large crustaceans and other fossils. Considering the nature of 

 the organic remains, and the evident position of the beds below the 

 lowest Old Red, Sir R. Murchison unhesitatingly considers these 

 Lanarkshire strata as the equivalents of the uppermost Ludlow 

 rocks or the Tilestones of England*. Amongst the principal fossils 

 found in this uppermost Silurian rock of Lanarkshire, is a species 

 of Pterygotus not to be distinguished from the species so abun- 

 dantly found in the Upper Ludlow rock of Shropshire and of Here- 

 fordshire, as well as Lingula cornea and Trochus helicites. The 

 same deposit contains numerous crustaceans of the group of Eury- 

 pteridce (Burmeister), which were described by Mr. Salter under the 

 * See Lyell's Manual of Elementary Geology, 5th edit. 1855, p. 420. 



