460 Geological Society. 



coarser shale, and consist chiefly of large teeth and vertebrae of a 

 species of Holoptychus and rays of Gyracanthus. 



The yard coal shale is still less fruitful than either of the other 

 seams, and has yielded only a few small teeth of Holoptychus, Cte- 

 noptychus, and some other unimportant fragments. 



On comparing these fossils with the Ichthyolites which he has 

 found in Lancashire, the author has ascertained that many are iden- 

 tical, but that others differ. The species of Diplodus, Ctenoptychus, 

 Megalichthys, Gyracanthus, one of Holoptychus r and Platysomus ? 

 exactly correspond in each district. In the Lancashire field he has 

 found remains of Ctenoptychus apicalis and C. denticulatus , which he 

 has not noticed in the Yorkshire ; and he is inclined to think, that 

 the former field is characterized, if there be a difference, by the 

 greater prevalence of Lepidoid fishes, and the latter by those of the 

 Sauroid family. 



The Ichthyolites occur chiefly in highly bituminous shales, with 

 the exception of the Ardwick limestone, and most abundantly where 

 it is finely grained. They are rarely associated with any quantity of 

 vegetable remains ; and this disposition of the two kingdoms, Mr. 

 Williamson is of opinion may assist in determining the conditions 

 under which the coal-measures were deposited. The Ichthyolites 

 also are in general more common in the roof than the floor of the 

 coal ; but in the cannel-seams of Wigan in Lancashire, and in the 

 thin seams connected with the limestones at Ardwick, they are most 

 abundant in the floor. They are rarely found in the coal itself, and 

 the instances in which they have been met with in that position by 

 the author, have been chiefly in the Middleton colliery. 



The manner in which Ichthyolites are associated with other re- 

 mains, Mr. Williamson states, is well worthy of attention. At Bur- 

 diehouse they occur in the midst of Unios, Cyprides, and Microconchus 

 carhonarius ; at Colebrook Dale, with species of Orbicula, Trochus, 

 Nautilus, Orthoceras, and Conularia ; in the lower measures of Lan- 

 cashire in beds nearly associated with those containing Goniatites 

 Listeri and Pecten papyraceus ; in the higher measures of Lancashire 

 and in Yorkshire, with Unionidse and Entomostraca ; at Middleton, 

 with Lingulse ; at the top of the series in Lancashire and Derbyshire, 

 with Mytili. 



TWEEDSIDE PHYSICAL AND ANTIQUARIAN SOCIETY. 



The stated quarterly Meeting of the Society was held on Novem- 

 ber 18, in the Library room, Kelso. The Duke of Roxburgh pre- 

 sided ; and the meeting was very numerous and encouraging, great 



