174 J. D. Dana — Sedgwick and Mukchison. 



A remarkable feature of the November paper is that it no- 

 where contains the term Upper Cambrian or even Cambrian, 

 although the rocks are Sedgwick's Upper Cambrian, together 

 with Murchison's Upper Siluriau. 



A second fact of historical interest is the use of the term 

 "Protozoie," not in the sense in which it was introduced by 

 him in 1838, but in that in which introduced in 1838 by Mur- 

 chison, on page 11 of his Silurian System, where he says : 



" But the Silurian, though ancient, are not, as before stated, the 

 most ancient fossiliferous strata. They are, in truth, but the 

 upper portion of a succession of early deposits which it may here- 

 after be found necessary to describe under one comprehensive 

 name. For this purpose I venture to suggest the term Protozoie 

 Mocks, thereby to imply the first or lowest formations in wdiich 

 animals or vegetables appear." 



These facts are in accordance with Sedgwick's acknowledg- 

 ment, mentioned on the preceding page. 



The map accompanying the paper as originally prepared, 

 had colors corresponding to five sets of areas, those of the 

 " Carboniferous Limestone," "Upper Silurian," "Protozoie' 7 

 flocks, " Mica and Chlorite Slate," " Porphyritic Rocks ;" and 

 here again Cambrian, Upper or Lower, does not appear, the 

 term Protozoie being substituted. The map, as it stands in 

 the Journal of the Geological Society, has in place of simply 

 Protozoie, the words " Lower Silurian (Protozoie)." Sedgwick 

 complains, in his paper of 1852, pages 151, 155, of this change 

 from his manuscript, and attributes it to Mr. Warburton, say- 

 ing that " the map with its explanations of the colors plainly 

 shows that Mr. Warburton did not comprehend the very drift 

 and object of my paper." " I gave one colour to this whole 

 Protozoie series only because I did not know how to draw a 

 clear continuous line on the map between the upper Protozoie 

 (or lower Silurian) rocks and the lower Protozoie (or lower 

 Cambrian) rocks." "Nor did I ever dream of an incorpora- 

 tion of all the lower Cambrian rocks in the system of Siluria," 

 Sedgwick also says on the same point : " I used the word Pro- 

 tozoie to prevent any wrangling about the words Cambrian and 

 Silurian." But this is language he had no disposition to use 

 in 1843, as the paper of 1843 shows. 



Page 155 has a foot note. In it the aspect of the facts is 

 greatly changed. He takes back his charges, saying, " I sus- 

 pect that, in the explanation of the blank portion of the rough 

 map exhibited in illustration of my paper I had written Lower 

 Silurian and Protozoie, and that Mr. Warburton, erroneously 

 conceiving the two terms identical, changed the words into 

 Lower Silurian (Protozoie) " " I do not by any means accuse 



