J. D. Dana—Address of T. Sterry Hunt. 99 
showing of what is not a pseudomorph preparatory to explaining 
what is; and observing, also, that this second part, the main 
part of the work, is treated, with the exception of a few 
examples unessential to the point in dispute, just as is done b 
Haidinger and all other writers on pseudomorphs, and contains 
a table, many pages long, of true cadadomorghs in which are 
those of serpentine, gieseckite (var. of pinite), steatite or tale, 
septolite and chlorite, besides other silicates. There is no fog in 
Delesse’s statements on this point. r. Hunt cites some 
seemingly opposing sentences from Delesse: but these relate to 
the exceptions, cases that for the most part are generally ad- 
mitted to be doubtful; they do not touch the species above- 
mentioned, those with regard to which Mr. Hunt would be glad 
to gather support from Delesse. 
Prof. Hunt says that Delesse’s views underwent a change 
about 1861, as appears in his work on metamorphism then pub- 
lished, in which Delesse “adopts” Mr. Hunt's view, that beds 
of serpentine have been formed from the alteration of chemically 
posited beds of a hydrous magnesian silicate related to 
Sepiolite (meerschaum). But the evidence is positive that, 
while Delesse accepted this hypothesis for beds of serpentine, he 
did not change his views on serpentine pseudomorphs. For in 
‘ear his paper on metamorphism appeared, after citing a long 
‘st of cases of envelopment from an article by Séchting, he 
¢ 
ees ip. 169) his chapter on pseudomorphs with the followin 
ien qu'elle soit plus ou moins modifiée dans sa composition et 
méme entiérement remplacée par une autre substance, il se 
q 
la géologi goes so 
far as to say (and this in 1866, it should be noted) that pseudo- 
morphic changes have often taken place on a grand scale, as has been 
“specially remarked by G..B 3 
& word of protest or objection, just as he did in his treatise of 
