PLATE I. 



Carboniferous Trilobites. 

 Phillipsia Derbiensis, Martin, sp. 1809. (P. 12.) 



Figs. 1 a and 1 b. — Head, from the Carboniferous Limestone, Boliand, Yorkshire. 

 (Gilbertson Coll.) Magnified four times. 1 a, top view; 1 b, side view of same. 

 Original specimen in the British Museum (Nat. Hist.), Cromwell Road, S.W. 



Figs. 2 a and 2 b. — A complete specimen from the Carboniferous Limestone, 

 Longnor, Staffordshire. Magnified three times. 2 a, side view ; 2 b, top view of same. 

 Original specimen in the Museum of Practical Geology, Jermyn Street, S.W. 



Fig, 3. — Detached head, from the Carboniferous Limestone, Settle, Yorkshire. 

 Magnified three times. Original specimen in the Woodwardian Museum, Cambridge. 



Figs. 4 a. — Entire specimen ; and 4 b. — Hypostome of same; from the " Rotten 

 stone " band of the Carboniferous Limestone, Matlock, Derbyshire. Fig 4 a, magnified 

 twice, and 4 b (the hypostome of 4 a), magnified four times. Original specimen in the 

 British Museum (Nat. Hist.). 



Fig. 5. — Detached head, from the Carboniferous Limestone of Castleton, Derbyshire. 

 Original specimen in the collection of the Rev. E. Oldridge de la Hey, M.A., Marple, 

 Cheshire. Magnified three times. 



Fig. 6. — Phillipsia Derbiensis, Martin, restored outline. 



Fig. 7. — g. Outline of glabella; c, outline of free cheek. 



Fig. 8 a, b. — Top view and section in outline of one of the thoracic somites. 



Fig. 9. — Outline restoration of pygidium, enlarged. 



