56 Transactions. 



centre, continuing beyond the distal extremity. To this stipe 

 are attached, at an angle of 30 degrees, the cellules, which are 

 beautifully ornamented with a kind of lace or network placed 

 around them from the outer margin to about half way on each 

 side of the solid axis ; the other two halves on the two sides of 

 the stipe being filled in with a kind of hairy, irregular network. 

 The cells at the outer edge are of a finely rounded or convex 

 shape, numbering about 26 to an inch, and are alternate on 

 opposite sides of the frond, while they gradually diminish from 

 three-quarters of its length to a lancet-shaped point. I think 

 there can be no doubt that there was a chitinous covering over 

 the fine hairy netting for protection that has been worn away. ' 

 Locality — Hartfell and Dobb's Linn. 



Genus Dicranograptus (Hall), species ramosus. — The polypery 

 towards the proximal point has a double row of cells, but divides 

 or bifurcates at a certain length up into two monoprionidian 

 branches on the outside only, or the polypery keeps the same 

 line as commenced at the proximal points, and has two small 

 lateral spines at each side of a minute radical. The structure of 

 DicranograjJtus ramosus (Hall) resembles the form of Diplograptus 

 for so far up, but the hydrothecce appear to have the same form 

 and structure as Cliniacograptus. The branching off of the two 

 ai-ms at a certain distance up make it easily distinguishable from 

 the other allied forms — Diplograptus and Cliniacograptus. The 

 genus Dicranograjjtus, as far as known, is entirely confined to 

 the upper Llandeilo rocks of Britain at present, but it is found 

 in the Cardaoc rocks in North America. Locality — Hartfell and 

 Dobb's Linn. 



Genus Pleurogra2:>tus (Prov.) — This large and rather remarkable 

 Gra[)tolite which we now take up is one of the branching forms, 

 and is, perhaps, one of the most curious of any of our British 

 forms, and seems to have some small- resemblance to. the Pleuro- 

 graptus, as figured by Mr Carruthers, or nearly related thereto. 

 Mr Carruthers had first given it the name of Cladograptis linearis. 

 The Generic name is one that was proposed by Genitz, but Mr 

 Can-uthers, not seeing it to be appropriate, then changed it to 

 Dendrograptus linearis. It is now recognised as Pleurograptus 

 linearis. The frond is composed of two long serrated branches 

 springing from a radical or initial point, and gives off branches 

 at certain distances and mostly at right angles to the main stems. 

 I have specimens with a third re-branching process given ofT, 



