154 Messrs. Barron 8f Hume — Eastern Desert of Egypt. 



wliich is distinctly narrower than that figured by me in 1883 (Pal, 

 Soc. Mon., pi. vi, figs. 7 and 8). 



The description given at pp. 33-34 closelj' agrees with our present 

 specimens, save in one particulai', namely, the axis is there stated 

 to be equal to half the entire breadth of the thorax, whereas in 

 Fig. 6 of our Plate VIJI it is shown to be exactly one-third the 

 entire breadth of the thorax. This form might therefore be 

 recognized as Griffithides longiceps, var. angusta, H. W. 



The following is a list of the Trilobites from the Carboniferous 

 Limestone in the Sheffield Museum, all from Derbyshire : — 

 Phillipsia Derbiensis, Martin, sp., 1809. 

 ,, gemmuUfera, Phillips, sp., 1836. 

 ,, JEichwaldi, Fisher, sp., 1825. 

 Griffithides globiceps, Phillips, sp., 1836. 



,, Carringtonensis, Etheridge MS. (H. W., 1884). 



,, longispinus, Portlock, 1843. 



,, seminiferus (a very good specimen in 'Rotten stone'), 



Phillips, sp., 1836. 

 ,, longiceps, Portlock, 1843. 



,, ,, var. angusta. (PL VIII, Figs. 6-8.) 



Bracliymetopus Ouralicus, De Verneuil, 1845 (a large series of very 



good detached head-shields and pygidia). 

 Proetus, sp. ind. (some small detached pygidia). 



Some large detached pygidia in this collection may be new. 



EXPLANATION OF PLATE VIII, Figs. 6-8. 



Fig. 6. — Griffithides longiceps, Portlock, var. angusta, H. "W. Carboniferous Lime- 

 stone: Stoney Middleboro'. 



Figs. 7, 8. — G. longiceps, var. angusta. Carboniferous Limestone: "Wettin Hill, 

 Derbyshire. 



Figures enlarged three times natural size. Original specimens preserved in 

 the Sheffield Museum. 



III. — Notes on the Geology of the Eastern Desert of Egypt, 

 By T. Barron-, A.E.C.S., F.G.S., etc., and W. F. Hume, D.Sc, A.E.S.M., etc... 



(By permission of the Under-Secretary of State for Public Works, and the 

 Director- General of the Survey Department.) 



The paper is divided into two parts, viz. : — 



1. Sedimentary Rocks. 



2. Igneous and Metamorphic Rocks. 



Part I. — 1. Pleistocene and Eecent. («) Igneous Gravel and Conglomerates. 



[b] Newer and older Beach Deposits. 



2. Pliocene. Nile Valley Limestones and Conglomerates. 



3. Miocene Beds. 



4. Eocene Limestones and Shales. 



5. Cretaceous Limestones. 



6. Nubian Shales and Sandstones. 



1. (a) Igneous Gravels, etc. — These consist of granite, gneiss, and 

 many other igneous and metamorphic rocks similar to those met 

 with in the Red Sea Hills, and occur up Wadi Qena and spread 



i 



