PLATE III. 

 Didymograptus— coM^mwed. 



FIGS. 



1 a — k. — Didymograptus Murchisoni, Beck. 



1 a. Imperfect specimen preserved on the surface of black limestone in very low relief, the 

 largest example figured by Sowerby, Murchison's Silurian System, pi. xxxvi, fig. 4. 

 Gelli, Llandrindod. Llandeilo. Mus. of Geological Society, London. 



1 b. Example with parallel stipes. Ibid. 



1 c. Preserved on dark grey shale. Holywell Burn, Shropshire. E. M. K. Wood's Collection. 



1 d. More diverging stipes. Ibid. 



1 e. Convei'ging stipes. Ibid. 



1/. Preserved in black shale and elongated by cleavage. Figured by Hopkinson and 

 Lapworth, Quart. Journ. Geol. Soc, 1875, pi. xxxv, fig. 2 a. Abereiddy Bay. 

 Llandeilo (Up. Llanvirn, Hicks). Woodwardian Museum. 



1 g. Somewhat wider form. Ibid. 



1 h. Showing converging and overlapping of distal portion of stipes. Figured ibid., 

 fig. 2 c. 



1 i. Specimen greatly elongated and of more uniform width. Abereiddy Bay. Llan- 

 deilo (Up. Llanvirn, Hicks). E. M. K. Wood's Collection. 



1 j. Well-preserved specimen. Ibid., fig. 2 b. Woodwardian Museum. 



1 k. Poorly preserved. Fig. 2/, ibid. 



2 a — j. — Didymocjraptus Mnrcliisnni, var. geminus, His. 



2 a. Reverse view. On same slab as type specimens of D. Murchisoni. Gelh, Llan- 



drindod. 

 2 b. Showing " furcillate " form. Figured, Murchison's Silurian System, pi. xxvi, fig. 4. 



Gelli, Llandrindod. 

 2 c. Ibid. 

 2 (7. Short and more typical form. Reverse view. Abereiddy Bay. Llandeilo (Up. 



Llanvirn, Hicks). Miss Elles' Collection, Cambridge. 

 2 e. Ibid. Reverse view. Abereiddy Bay. 

 2/ Ibid. 

 2 g. Obverse view. Holywell Burn, Shropshire. Lower Llandeilo. E. M. R. Wood's 



Collection. 

 2 h. Imjjerfect. Type specimen of D. furcillatus, Lapw. Figured by Hopkinson and 



Lapworth, Quart. Journ. Geol. Soc, 1875, pi. xxxv, fig. Sa. Abereiddy Bay. 



Llandeilo. Woodwardian Museum. 

 2 i. Obverse view. Ibid., fig. 3 c. 

 2j. Ibid., fig. 3 b. 



