376 PEOCEEDiNGs OP THE GEOLOGICAL SOCIETY. [March 22, 



M. Lefevre, writing at the same time, confirms the observation of 

 Enssegger about the occurrence of the conglomerate. " Near 

 Khartoom, on the Libyan side, you meet on the redans of the 

 "White Nile with a modem conglomerate composed of fragments of 

 sandstone united by a calcareous cement, either deposited by the 

 water of the river or filtered through the alluvial soil. This con- 

 cretionary deposit is exhibited equally on the banks of the Blue 

 Kile, and it is well seen on either side where the banks are perpen- 

 dicular." He adds that the alluvial escarpment is nowhere higher 

 than from 50 to 56 feet. 



In his ' Eeisen,' Eussegger describes the occurrence of the human 

 bones at Duntai in terms somewhat difii'erent from those employed in 

 his " Briefe " in the ' Jahrbuch.' " The freshwater alluvia occurring 

 at Karkodije and Seru extend, with the sKght modifications already 

 indicated, up the Blue Eiver as far as Eosserres, forming a hillocky 

 alluvial track ; and in this instance I must observe that in the an- 

 cient mud- conglomerate of Geivan we found portions of Mimosa- 

 wood completely converted into lignite, and, at the village of Duntai, 

 near Seru, calcined (verkalkt) human bones in the incipient stage 

 of bitumenization*. A kind of bitumen, or rather highly bitumi- 

 nous hgnite, also occurs, although sparingly, at Geivan, and, ac- 

 cording to my observation, only in small elongated nodular pieces, 

 which in their transverse fractures display a concentrically laminated 

 structure, resembling the annual growth of wood, and burning with 

 a brief flame only, but emitting a very smoky and bituminous odour." 

 On neither occasion does Eussegger specify what these fossil human 

 bones were, nor am I aware that any detailed identification of them 

 has been published. But the case is of sufficient importance to de- 

 mand the attention of future explorers of the Nile vaUey to a walk 

 of observation which may yield results of high importance. Captain 

 Grant informs me that neither Captain Speke nor he ever met with 

 fossil bones along their route. Besides the asserted human bones at 

 Duntai (about halfway between Sennaar and Eosserres), Eussegger 

 mentions, cursorily, that in the conglomerate of Woadd Medineh, 

 also on the Blue Nile, he encountered a kind of sandstone-mass 

 containing bones, which he took to belong to the foot of a young 

 Camel. Dr. Murie, who accompanied Mr. Petherick on his return 

 to Soudan, has shown me specimens of an alluvial fine-grained sili- 

 ceous grit or conglomerate from the White NUe, above Khartoom, 

 which is full of shells of Oyrena fiuminalis. The observations of 

 Eussegger, Mr. Leith Adams, and Dr. Murie agree as to the abun- 

 dance of the shells of Mollusca in the Nilotic alluvia, mud, or con- 

 glomerate, from the neighbourhood of the First Cataract upwards, 

 and along the course both of the Blue and White Elvers — oyster- 

 banks of j3^iheria Caillaudl occurring throughout. 



* The original passage stands thus : — " Und ich glaube diessfalls nur bemer- 

 ken zu mussen, dass wir in dem altern Flusschlamm-Konglomerate bei G-eivan 

 Stiicke von Mimosenholz das ganz in Braunkohle umgewandelt war, und am 

 Dorfe Duntai bei Seru Menschenknochen fanden verkalkt und im Zustande einer 

 beginnenden Verkohlung." (Eussegger, ' Eeisen,' Band ii. pt. 2. p. 717.) 



