1 88 EVIDENCE OF THE FOSSIL FLORA. 



sures, in a style which cannot fail to delight the heart of 

 every assertor of the development hypothesis, I present them 

 to the reader from Mr Dick's specimen, in a figure (fig. 61) 

 which, however slight its interest, has at least the merit of 

 being true. The stone exhibits specimens of the two species 

 of Mr Clouston's collection, — the sharp-edged, finely-striated 

 weed, a, and that roughened by tubercles, h ; which, besides 

 the distinctive character manifested on its surface, difiers from 

 the other in rapidly losing breadth with every branch which 

 it throws off, and, in consequence, running soon to a point. 

 The following cut (fig. Q2) represents not inadequately the 



Ficr. 62. 



a. Smooth-stemmed species. b. Tubercled species. 

 Natural size.) 



cortical peculiarities of the two species when best pre- 

 served. The surface of the tubercled one may perhaps re- 

 mind the algologist of the knobbed surface of the thong or 

 receptacle of Himanthalia lorea^ a recent fucoid, common on 

 the western coast of Scotland, but rare on the east.* An 

 Orkney specimen lately sent me by Mr William Watt, from 

 a quarry at Skaill, has much the appearance of one of the 

 smaller ferns, such as the moor-worts, sea spleen-worts, or 

 maiden-hairs. It exists as an impression in diluted black, on 

 a ground of dark gray, and has so little sharpness of outline, 

 that, like minute figures in oil-paintings, it seems more dis- 



* It is Sir Roderick Murchison's opinion that all the fossil plants of 

 Caithness belonged to the land. — L. M. 



