12 Proceedings of the Boyal Physical Society. 



(Chilognatlious myriapods of the genera Kampecaris and 

 Archidesmus), associated with those of plants of the genera 

 Psilophytoii and Arthrostigma, are comparatively abundant 

 in the finer sediments, and point conclusively to the close 

 proximity of land. 



Along the southern margin of the central basin there is 

 interesting evidence to prove that there must have been 

 irregular movements of elevation and depression during the 

 Lower Old Eed Sandstone period. For example, in the 

 neighbourhood of Lesmahagow, a perfect passage occurs from 

 marine strata of Upper Silurian age into reddish beds, pro- 

 bably of lacustrine origin, indicating that an upward move- 

 ment had elevated a portion of the sea-floor into a lake basin. 

 A few hundred feet from the base, however, certain beds are 

 found, almost identical with the underlying marine Silurian 

 strata, and containing similar fossils pointing to a temporary 

 removal of the barrier, and the return of marine forms. These 

 marine bands are overlain by a great thickness of lacustrine 

 deposits, till about 5000 feet from the base we find remark- 

 able evidence of another return to marine conditions. At 

 Carmichael, in Lanarkshire, a band of shale has yielded a 

 graptolite, Orthoceras, Beyrichia, etc. — forms which must 

 have survived in the open sea since Upper Silurian time. 

 The conditions favourable to their existence in the Old Eed 

 Lake could not have continued for any length of time, as this 

 band of shaleis succeeded byagreat development of sandstones, 

 shales, and conglomerates, indicating a prolonged continuance 

 of lacustrine conditions. An interesting discovery of a speci- 

 men of Cephalaspis has recently been made by Dr Hunter of 

 Braid wood in the Old Eed Sandstone at Lesmahagow, which 

 has been submitted to Dr Traquair for identification. 



Such interesting palseontological evidence, scanty though 

 it be, conclusively points to the incursions of marine life into 

 the inland Old Eed lakes. It cannot be doubted that the 

 marine life in the early part of the Lower Old Eed Sandstone 

 period w^ould be of a Silurian type ; but the period was so 

 protracted, that I have no doubt that it embraced the time 

 represented by the marine life of the Lower and Middle 

 Devonian formations of England and the Continent. 



