152 



SCIENCE. 



[N. S. Vol. V. No. 108. 



Hastings sand, when generally it lay always on 

 the Weald clay. 



The change effected on land and sea areas at 

 the end of the Jura period was on a very grand 

 scale in Europe as well as in America ; and the 

 Neocomian or Lower Cretaceous was not de- 

 posited in many portions of central Europe, 

 especially in England, except at the little corner 

 of Speeton, on the Yorkshire coast; and in the 

 United States the Neocomian, even more limited 

 than in Europe, was confined to Texas, the 

 Indian Territory and southern Kansas. 



One word of explanation on the use in France 

 and Switzerland of the name 'Puberckian,' to 

 designate the upper Tithonic or Berriasian. 

 From the beginning, in 1848 and 1859, 1 showed 

 that the name was wrongly applied to strata 

 much younger than the Purbeck beds of Eng- 

 land. The position of the Hemicidaris Purbeck- 

 ensis, found in the first beds of the Salins lime- 

 stone, authorize the correlation of the Puberck- 

 ian of England with the base of the calcaires 

 porlandiens or Lower Tithonic of the Jura. 

 And the Purbeckian of the Jura Mountains, 

 so well described by Gustave Maillard in his 

 well known monograph {Mem. Soc. Paleonf. 

 Suisse, Vol. XL, Geneve, 1884), correspond 

 and is the equivalent of the lower portion 

 of the Spilsby sandstone of Lamplugh and Pav- 

 low ; it is to say, it represents in the Jura the 

 base of the Speeton clay of England, instead of 

 being correlated to the Purbeck beds of the 

 Island of Portland. 



CORRELATION OF THE ENGLISH AND BAST 

 FRENCH FORMATIONS. 



England. 

 Tealby limestone. 

 Tealby clay. 



Claxby ironstone. 

 Spilsby sandstone. 



Eastern France. 

 Urgonian or 

 Upper Neocomian. 

 Hauterivian or 

 Middle Neocomian. 

 Valengian or 

 Lower Neocomian. 



Weald clay. 



Hastings sands. 

 Purbeck beds. 



Jura — Portlandian limestone. 

 Ard^che— Upper, Middle and 

 Lower Tithonic. 



Portland stone or Portlandian marls or 



Exogyra virgula zone. Exogyra virgula zone. 



The correlation of the Wealden of England 

 with the Tithonic of Franche-Comte, Switzer- 

 land, Savoy, Dauphin6, etc., is a beautiful 

 work awaiting the careful researches of English 



geologists, and it is to be hoped that Mr. George 

 William Lamplugh, now on the staff of the Geo- 

 logical Survey, who has done such good service 

 at the geology of Speeton, will continue the 

 work so well begun forty-eight years ago by 

 Edward Forbes, so well traced in 1855 by John 

 Phillips, and now so well advocated by Prof. 

 O. C. Marsh. 



Jules Marcou. 

 Cambridge, January 1, 1897. 



COMPLIMENT OR PLAGIARISM. 



The carefully prepared reply of Professors 

 Beman and Smith (Science, p. 61) is disingen- 

 uous. Professor Halsted would gladly have 

 printed in parallel columns the whole of his sec- 

 tion. Partition of a Perigon (Elements,151), which 

 reappears in Beman and Smith, p. 179, as ' Par- 

 tition of the Perigon.' As I made this section 

 myself, I feel safe in asserting that it never be- 

 fore occurred in any geometry in the English 

 language ; but how could I ask the editor of 

 Science to reprint it simply because Professors 

 Beman and Smith had reprinted it? They de- 

 liberately say, "the order of the problems : To 

 bisect a perigon, to trisect a perigon, to cut a 

 perigon into five equal parts, to cut a perigon 

 into fifteen equal parts," etc., "maybe found 

 in Newcomb's Geometry." (Science, p. 61.) 



With Newcomb's book now in my hand, I 

 assert that not one of these problems occurs 

 therein. Next they assert that the word ' peri- 

 gon ' is ' found in several geometries. ' If, in 

 English, they mean Halsted' s Metrical Geom- 

 etry, 1881 ; Halsted's Elements, 1885 ; Hal- 

 sted's Elementary Synthetic, 1892 ; Beman and 

 Smith, 1895. The statement is disingenuous. 

 If they knew of any other they would have 

 named it. 



George Bruce Halsted. 



the meteorological conference at PARIS. 

 A CORRECTION. 



On page 17 the last sentence of the first para- 

 graph of my report should read as follows : 

 "No one came from either Spain or Brazil, as 

 was not the case at Munich, but Italy, Belgium, 

 Canada and Mexico each sent a delegate to 

 Paris, the two latter countries participating 

 for the first time in an iijternational meeting." 



