PLATE IV. 



D idy m OgraptuS — continued. 



FIGS. 



1 a — -/. — Didymograptus hifidus. Hall. 



1 a. Presei-ved in black shale. Fis^^ured bj Hopkinson and Lapwortb, Quart. Journ. 



Geol. Soc, 1875, pi. xxxiii, fig. 8 a. Porth-bayog, Ramsey I. Up. Arenig. Wood- 



wardian Museum. 

 1 h. Ibid., fig. 8 d. 



1 c. Larger specimen in relief. Pont Seiont. Up. Arenig. Woodwardian Museum. 

 1 d. Ibid. 

 1 e. Large specimen, preserved partly in relief, partly as a cast (labelled D. Murchisoni) . 



I3 miles S.E. of Duleek, co. Meath. Museum of Geol. Surrey, Ireland. 

 1/. Widely divergent stipes. Pont Seiont. Up. Arenig. Woodwardian Museum. 



2. — Didymograptus stahilis, Elles and Wood, sp. nov. 



Specimen redeveloped. Originally figured by Hopkinson as D. indentvs. Quart. Journ. 

 Geol. Soc, 1875, pi. xxxiii, fig. 7 a. Porth-hayog, Eamsey I. Up. Arenig. Wood- 

 wardian Museum. 



3 a — c. — Didymograptus anq^lus, Elles and Wood, sp. nov. 



3 a. Obverse vieAv. Preserved in black shale. Abereiddy Bay. Llandeilo (Up. Llanvini, 



Hicks). G. L. Elles' Collection. 

 3 b. Large specimen, affected by cleavage. Abereiddy Bay. E. M. E. Wood's Collection. 



3 c. Specimen not much cleaved. Abereiddy Bay. Woodwardian Museum. 



4 a — c. — Didymograptus, cf. indentns, Hall. 



A- a. Badly preserved example. Mungrisedale, Glenderamakin Valley, Lake district. Upper 

 Arenig. Woodwardian Museum. 



4 6. Ibid. 



4 c. Poorly preserved. Figured by Nicholson as D. geminus, Ann. Mag. Nat. Hist.. 187u, 



p. 346, fig. 6 a. Thornship Beck, Lake district. Up. Arenig. Woodwardian 

 Museum. 



5 n — h. — Didymograptus nanus, Lapw. 



5 a. Poorly preserved specimen affected by cleavage. Figured by Hopkinson and 



Lapworth, Quart. Journ. Geol. Soc, 1875, pi. xxxv, fig. 4 <?. Abereiddy Bay. 



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

 5 h. Ibid., fig. 4 h. 



5 c. Quarry N.W. of Llanvirn. Lower Llanvirn (Hicks). Woodwardian Museum. 

 5 d. Outerside, Keswick. Upper Skiddaw Slates. British Museum (Nat. Hist.), S. 



Kensington. 

 5 e. Reverse view. Quarry N.W. of Llanvirn, Lower Llanvirn (Hicks). E. M. K. 



Wood's Collection. 

 5/. Preserved jiartly in relief, partly as a cast. EUergill, Lake District. Lapworth's 



Collection. 

 5 g. Ibid. 



5 h. Poorly preserved specimen. ? Figured Salter, Quart. Journ. Geol. Soc, vol. xix, 



p. 137, fig. 13 c. Eggbeck, Ullswater. Upper Skiddaw Slates. Museum of Practical 

 Geology, Jermyn Street. 



6 a — d. — Didymograptus artus, Elles and Wood, sp. nov. 



6 a. Large specimen. Thornship Beck. Upper Skiddaw Slates. Woodwardian Museum. 

 6 b. Two specimens showing effect of cleavage. Porth-hayog, Eamsey I. Upper Arenig 



(Hicks). G. L. Elles' Collection. 

 6 c. Porth-hayog. Woodwardian Museum. 

 6 d. Obverse view. Porth-hayog. G. L. Elles' Collection. 



