Dana.] 168 [November 4, 



repeated by him in the successive numbers of the Geological Annual, 

 published by himself and Mr. Lapparent. In the number published 

 in 1872, he mentions, on page 243, the pseudomorph, talc after ensta- 

 tite. He has another theory for the formation of beds of serpentine 

 and steatite; but he has not put into that category, in any state- 

 ment I have seen, distinct pseudomorphous crystals consisting of 

 serpentine or steatite. 



Naumann, the eminent mineralogist, crystallographer and geologist, 

 commended Delesse's judicious chapter on " envelopment." There- 

 upon, Mr. Hunt has claimed that Naumann adopts his own view of the 

 envelopment theory. In fact, Naumann's Mineralogy contains through- 

 out the ordinary views on pseudomorphism, and many examples are 

 given. Moreover, in the Jahrbuclifur Mineralogie und Paleontologie, 

 for November, 1872, he has a letter correcting in strong language the 

 statement of his views on pseudomorphism, made by Mr. Hunt in his 

 American Association Address. Naumann's letter closes with the 

 remark that " only an incomprehensible misunderstanding can ac- 

 count for his statement, which has already been sufficiently refuted 

 by Mr. Dana in the American Journal of Science for February 

 and August of 1872." 



Mr. Hunt says, in his notice of Dr. Genth's paper, that "the advocates 

 of the doctrine of transmutation [by which he means pseudomorph- 

 ism as it is held by most writers] have not hesitated to assert, upon 

 this supposed evidence [that of ' examples of replacement and envel- 

 opment '] the conversion of almost every mineral species into some 

 other, and to extend this view to rock-masses, declaring that the 

 great part of all the so-called metamorphic or crystalline rocks are 

 the results of an epigenic process; a doctrine that has been em- 

 bodied in the doctrine of Prof. Dana, that ' regional metamorphism 

 is pseudomorphism on a broad scale.'" And he adds, "while the 

 advocates of this doctrine maintain that a mass of granite or diorite 

 may be converted into serpentine or limestone, and that a limestone 

 may be changed into granite or gneiss, which may in its turn, become 

 serpentine, it is evident that it makes little difference what mineral 

 species is taken for the starting point." 



Now the above, whether regarded as referring to my views, or to 

 those of other writers on pseudomorphism, needs profound modifica- 

 tion to make it just and true. As to that " dictum" of mine (a clause 

 in a sentence of a book notice, published in the " Journal of Science," 

 Vol. xxv, p. 445, 1858), I told him, in my review of his Address, in 



