Professor J. W. Gregory — On the Coral Octotrernacis. 9 



overlying Nubian Sandstone is frequently tilted at high angles (60° or 

 over). The succeeding upper sandstones and Cretaceous strata dip 

 westward from the range at an average of 35°, while the overlying 

 Miocene gypsums and clays have their inclination reduced to 20°. 

 The upper beds of the gypsum only dip 10°, and the Pliocene 

 formations capping the series 4° to 6°. The Nubian Sandstone, which 

 on the west flank is some thousand feet thick, on the eastern flank of 

 the range is reduced to an intensely crushed band, only a few yards 

 in width, immediately overlain by gypsum. It is obvious that the 

 comparative horizontality of Pliocene and Miocene beds at the surface 

 may mask highly disturbed conditions in the strata underneath. 



Puller details are about to be issued on these very interesting 

 questions in a, " Report on the Oilfields Region of Egypt" now in 

 the press, where the results of the writer's researches in this region 

 during several years have been summarized. In this connexion 

 I might also call attention to the new volume on the Geography and 

 Geology of West Central Sinai by my colleague Dr. John Ball, in 

 which some of the fine faulting along the edges of the Gulf of Suez 

 to the north of the oilfield region is clearly illustrated on Plate xvii. 



Through the kind permission of the Director-General I am enabled 

 to send a small map and diagrammatic sketch section of the region 

 specially dealt with, which has become of great economic interest on 

 account of the developments of the petroleum industry in two 

 portions of its area. The occurrence has raised a number of interesting 

 physical and chemical questions, which are now being carefully con- 

 sidered, as a large number of analyses of the deep-seated waters have 

 been made in the Egyptian Government Analytical Laboratory, and 

 the results plotted at the Geological Survey. 



III. — OCTOTREMACIS, ITS STRUCTURE, AFFINITIES, AND Age. 

 By J. W. Gregory, D.Sc, F.E.S., of Glasgow University. 



THE Javan fossil corals collected by the Austrian frigate 

 Novara included a specimen on which Reuss (1866, p. 172) 

 founded a new genus, Polysolenia. He described it (ibid., p. 172) as 

 showing in the structure of its coenenchyma " eine uberraschende 

 Ahnlichkeit mit Polytremacis und Ileliopora" . "Das Conenchym 

 besteht aus langen, ziemlich dicken, geraden, neben einander 

 liegenden Rohren." These tubes, according to his account, occur in 

 circles of six around a central tube. Reuss repeated (p. 174) that 

 the coenenchyma is composed of regular parallel tubes (Rohren), 

 whereby it is closely allied to Heliopora and Polytremacis. He 

 named it Polysolenia "nach ihrer rbhrigen Structur". Reuss' 

 illustrations suggested some suspicion as to the accuracy of his 

 description, since the dark parts of his figures might be interpreted 

 as the original solid structures of the coral, and the light parts as the 

 matrix. If so, the coenenchyma would be trabecular and the septa 

 a series of thin lamella. Reuss, however, was emphatic that the 

 septa are thicker than the walls of the supposed ccenenchymal canals; 

 and, if so, the light parts of the figure represent the original solid 



