90 Correspondence — Sir William Bauson, C.2I.G. 



tracts. I understand that Captain Lyons intends to visit England 

 early in the ensuing summer in order to select a staff of young 

 geologists to work under him in Egypt. Ample provision has been 

 made in the estimates for equipment, tents, camels, and attendance. 

 It will of course only be possible to carry on outdoor work during 

 six months in the year; but the geological structure of the country 

 is of great interest, though on the whole, simple; and the formations 

 are distributed on a large scale. For young geologists who wish to 

 extend their knowledge of other countries the work ought to prove 

 attractive, and with clue care, will be healthy. Camping in tents in 

 the desert is, as I can state from experience, exceedingly enjoyable, 

 and when to this is added the delight of riding on camels and 

 donkeys, there is nothing more to be said in order to secure 

 numerous volunteers for the work ! Edwabd Hull. 



ERRATUM AND NOTE TO ARTICLES ON EOZOOX. 



Sir, — I observe in the beginning of the second paragraph of my 

 Article in December 1895, p. 545, an error which may puzzle some 

 readers. The words " old calcite and serpentine lagoons" should be 

 "calcite and serpentine layers." A less important error is the 

 substitution of the name " Lome " for " Lowe " in the description 

 of Fig. 2 in my first Article in October 1895, p. 447. 



In the second Article I should perhaps have mentioned that in 

 the Glauconite Limestone of Levis (Ordovician), and in that of 

 Kempfen, Bavaria (Eocene), as well as in Cretaceous and Modern 

 greensands, while some grains of glauconite fill cavities of fossils, 

 others, and often the great majority, are independent and amorphous. 

 Thus in mode of occurrence the hydrous silicates of later limestones 

 do not differ from that in the Grenville Limestone. 



January 3, 1896. Wit. DawSON. 



ON THE TRUE MEANING OF THE TERM BOLDERIAN. 



Sir. — Professor Dewalque, of Liege, in a letter you have lately 

 published (1st December, 1895), criticizes the use I made of the 

 term "Bolderien," established by Dumont, for some beds of the 

 Belgian Tertiary formation. But this courteous censure seems to 

 me without sound ground, and I think he has misunderstood 

 Dumont's statements. 



If we turn to the Journal of the Boyal Academy of Brussels, 

 for 1849, where Dumont created the term " Bolderian," we read : 

 " The Bolderian system is divided into two stages ; one is a marine 

 stage in which the lower part consists of glauconiferous sands, and 

 the upper part is composed of yellow sands, in these come, in 

 order, the fossiliferous sands of the Bolderberg; the other stage is 

 a fresh-water formation, consisting of sands and lignite, of which 

 traces are found under the Campinian deposit." 



There is no doubt about this, the type of the Bolderian system, in 

 its lower part, is indicated as composed of marine fossiliferous sands 

 found in the hill of Bolderberg, near Hasselt, and includes the 

 fossiliferous bed so well known in that locality. 





