PLATE XXIX. 



Sub-genus Orthograptus. 

 Figs. 



1 a — d. — Orthograptus mutabilis, Elles and Wood, nov. (Page 232.) 



1 a. Large typical specimen, reverse aspect. Dobb's Linn. Birkhill 



Shales. Lapwortli's Collection. 

 1 b. Smaller specimen, obverse aspect. On same slab as fig. 1 a. 

 1 c. Short, broad specimen, reverse aspect. Ibid. 



1 d. Distal portion, compressed, doubtfully referable to this species. 



Ibid. 



2 a — e. — Orthograptus bellulus, Tornquist. (Page 231.) 



2 a. Typical specimen, showing long virgella. Dobb's Linn. Upper 



Birkhill Shales (Monog. Glingani band). Geological Survey of 



Scotland. 

 2 b. Narrower specimen. Ibid. Lapwortli's Collection. 

 2 c. Ibid. 

 2 d. Well-preserved specimen. Plewlands Burn, Raehills, Moffat. 



Birkhill Shales. Geological Survey of Scotland. 



2 e. Small specimen in relief, reverse aspect. Skelgill, Ambleside. 



Stockdale Shales. British Museum (Natural History), S. 

 Kensington. 



3 a — e. — Orthograptus truncatas, Lapworth. (Page 233.) 



3 a. Typical specimen. Mount Benger Burn. Hartfell Shales (zone 



of Dicranog. Glingani), Lapwortli's Collection. 

 3 b. Ditto. On same slab as fig. 3 a. 

 3 c. Smaller form, showing more gradual increase in width. Dobb's 



Linn. Hartfell Shales (zone of Dicranog. Glingani). Geological 



Survey of Scotland. 

 3 d. Characteristic form. Hartfell Spa. Hartfell Shales (zone of 



Dicranog. Glingani). Wood's Collection. 



3 e. Ditto. Elles' Collection. 



4 a — e. — Orthograptus truncatas, var. intermedins, Elles and Wood, nov. (Page 23G.) 



4 a. Short, but typical specimen. Hartfell. Lower Hartfell Shales 



(zone of Glimacog. Wilsoni). Lapwortli's Collection. 

 4 b. Long distal portion. Ibid. Elles' Collection. 

 4 c. Proximal portion, reverse aspect. On same slab as fig. 4 b. 

 4 d. Very long, complete specimen. Hartfell Shales (zone of Dicranog. 



Glingani). Lapworth's Collection. 

 4 e. Long distal portion. Hartfell Shales (zone of Glimacog. Wilsoni). 



Wood's Collection. 



