PLATE XXXV. 



Genera Trigonograptus and Dimorphograptus. 



Figs. 

 1 a — c. — Trigonograptus ensiformis (Hall). (Page 302.) 



1 a. Typical specimen with sicnla P Mosedale Beck, Trontbeck. 



Skiddaw Slates. Sedgwick Museum. 

 1 b. Distal fragment, narrower. Pont-y-Feni Quarry, 3 miles W. of 



St. Clears. Arenig. Geological Survey of England and 



Wales. 

 1 c. Long, narrow specimen. Near Keswick. Skiddaw Slates. 



Sedgwick Museum. 



2. Trigonograptus ensiformis, var. lanceolatus (Nicholson). (Page 303.) 



Type specimen, figured Nicholson, 'Ann. Mag. Nat. Hist.,' LS69 [4], 

 vol. iv, pi. xi, fig. 6. Ellergill, near Milburn. Skiddaw Slates 

 (Ellergill Beds). British Museum (Nat. Hist,). 



3 a — (/. — Dimorphograptus confertus (Nicholson). (Page 344).) 



3 u. Typical specimen, distorted by cleavage. Skelgill. Skelgill 



Beds (zone of Dimorphog. confertus). Sedgwick Museum. 

 3 b. Well-preserved specimen. Main Cliff, Dobb's Linn. Birkhill 



Shales (zone of Orthog. vesiculosus). Elles' Collection. 

 3 c. Specimen showing sicula and virgella. Urr Water, ^ mile S.W. 



Nether Glaisters, 1\ miles S.W. Dunscor. Birkhill Shales. 



Geological Survey of Scotland, Edinburgh. 



3 d. Well-preserved short specimen. Long Cliff, Dobb's Linn. 



Birkhill Shales. Lap worth's Collection. 



•1 a — -/. — Dimorphograptus confertus, var. Swanstoui (Lapworth). (Page 350.) 



4 a. One of type specimens, figured Lapworth, ' Geol. Mag.,' 1876, 



pi. xx, figs. 13 a — c. Coalpit Bay, Donaghadee. Birkhill 

 Shales. Belfast Natural History Museum, 



4 b. Another typical specimen on same slab as 4 a. 



4 c. Ibid. 



4 d. On reverse side of same slab. Ibid. 



4e. Longer specimen. Coalpit Bay, Donaghadee. Birkhill Shales. 



Lapworth' s Collection. 

 4/. On same slab as 4 e. 



5 a — e. — Dimorphograptus decussatus, Elles and Wood, nov. (Page 352.) 



5 a. Typical specimen. Dobb's Linn. Birkhill Shales (zone of 



Orthog. vesiculosus). Elles' Collection. 

 5 b. Somewhat smaller specimen, obverse view. Main Cliff, Dobb's 



Linn. Ibid. 

 5 c. Reverse view. Same locality as 5 a. Ibid. 

 5 d. Poorly preserved specimen. Same locality as bb. Ibid. 

 5 e. Young specimen showing proximal end and virgella. On same 



slab as 5 a. 



6. Dimorphograptus decussatus, var. partiliter, Elles and Wood, nov. (Page 353.) 



Characteristic specimen. Main Cliff, Dobb's Linn. Birkhill Shales. 

 Elles' Collection. 



