180 REPORT OF THE AMERICAN COMMITTEE. 
possibility that it may have been formed in other ways and from 
other rocks." [The plain meaning here is that Capt. Dattou is 
convinced that in many instances known to himself, serpentine is 
an alteration-product of one eruptive rock, and he thinks it likely 
that it may be an alteration-product of other rocks, but he nowhere 
implies that it may itself be an original eruptive. The inference, 
therefore, is that he votes " No." — Rep.] 
Prof. Pumpelly: "No." 
Prof. A. Winchell : " I think not." 
Out of fourteen opinions, not one approves the selection of Ser- 
pentine as the type of a group of eruptive rocks. Thirteen reject 
it monosyllabically or by plain implication, viz.: Dana, Daw- 
son, Hunt, Irving, Emmons, G. H. Williams, Hitchcock, 
Winchell, Wadsworth, Emerson, Dutton, Pumpelly and 
A. Winchell. 
Prof. Le Conte's answer is not definite, but is probably " No." 
It may fairly be said that the bias of American opinion is 
against the acceptance of this as a class of eruptive rocks. 
N. Is Serpentine (1) sometimes or (2) always an altera- 
tion product (3) OF eruptives, or (4) OF sedimentary 
ROCKS, OR (5) OF either ? 
Prof. Dana : "Serpentine occurs as a metamorphic eruptive, 
metamorphic sedimentary, or metamorphic metamorphic rock; 
not as an unaltered eruptive." 
Sir J. W. Dawson : "There may be eruptive serpentines, but 
I have not met with them. Serpentines, in my experience, are 
of three kinds : (a) intrusive rocks hydrated ; (b) igneous veins 
(chrysolite, etc.); (c) beds and concretions in calcareous beds, e.g., 
Laurentian limestones. They diifer in composition as well as in 
origin." 
Dr. T. Sterry Hunt: "Serpentine is an indigenous rock of 
aqueous origin, and not a product of alteration." 
Prof. Le Conte: "I believe that Serpentine is always an 
alteration-product — sometimes of eruptives, but more commonly, 
in my experience, of sedimentaries." 
Dr. Emmons: "Serpentine is always the product of alteration 
of some other rock or mineral, and probably quite as often of 
sedimentary as of eruptive rocks or minerals." 
