FOUND AT LAXEYj ISLE OF MAN. 217 



pointed^ nearly equal in size and lengthy surface nearly 

 smooth. The branches in the lower part are thick com- 

 paratively to their length. The surface of the stem appears 

 to be smooth, and affords no evidence of strise or scales. 



The stone in which the plant is imbedded is a fine-grained 

 grit of a grey colour ; and the specimen itself is of a yellow 

 tint, as if coloured by oxide of iron ; it runs nearly at 

 right angles to the bedding of the stone, and appears as if 

 standing in the same position in which it had grown. The 

 stone is a rolled one, but it is evidently from the Manx 

 schists found in the vicinity. These, according to Professors 

 Harkness and Nicholson, are of the age of the Skiddaw 

 slates ; but the rock in which the fossil occurs may be of 

 older date, as some of the lower portions of the series have 

 not yet been clearly determined. Here, therefore, we have 

 evidence of a plant in the lowest part of the Silurian for- 

 mation, or even lower. By diligent search the rock in which 

 the specimen occurs may probably be found in situ in the 

 upper part of the Laxey valley. The great resemblance (if 

 not identity) of the Manx to the American specimen is very 

 remarkable, and shows the similarity of conditions then 

 prevailing in distant parts of the globe. The specimen 

 might have been called Psilophytum cornutum, if any 

 marking on the surface of the stem had been observed; but 

 as these appear to be absent, it is proposed to call it Psilo- 

 phytum Monense. As to the nature of the water in which 

 it grew, there is no evidence from organic remains; but in 

 its characters it more resembles a Fucoid than a land plant. 



