Wadsworth.] 
260 
[October 19, 
Melaphyr. 
No. 209 (407) is held to be an altered andesite, containing 
much quartz as a product of decomposition. The larger crystals 
and the blackish grains described by Zirkel, which he regards as 
augite or unknown, I hold are the remains of the hornblende so 
common in the andesites (Bull. Mus. Comp. Zool. 1879, V, 280, 
281). Nos. 203 (313), 204 (314), 205 (321), 206 (326), 207 (332), 
208 (340), are regarded by me as melaphyrs, that is, altered 
basalts, and they contain much alteration quartz. No. 208 (340), 
I hold to be. a melaphyr as defined by me. 
Propylite. 
Since this rock has attracted much attention from its relation 
to silver mining and from its forming the base of the classification 
proposed by Richthofen and adopted, with modifications, by King, 
it demands a somewhat extended notice. 
It is first necessary to give some lengthy extracts from the 
writings of Messrs. King, Hague, Emmons, and Zirkel, in order 
that its “ habitus ” may be understood. The italics in the extracts 
are mine. 
Mr. King states (I, p. 550, 551) : “ The science of petrography 
offers no more interesting example of the delicate shades on 
which lines may be successfully drawn than the case of this rock. 
Richthofen’s subtle observation and great practice as a field geol- 
ogist enabled him to detect the essential characteristics of the 
habitus of this rock, while at the same time he clearly saw its re- 
lations to the other hornblende-plagioclase species. The subse- 
quent microscopic analysis of the rock by Zirkel has firmly 
established its independence as a species. The English petro- 
graphers especially have been inclined to deny its. existence ; but 
the shade of habitus upon which Richthofen founded his first 
assertion of the species is so evident in the field of the Fortieth 
Parallel Exploration that there has never bee?i the slightest doubt 
on the part of Messrs. Emmons and Hague and myself as to the 
identity of propylite. When the large collection of specimens 
brought in by us came to be studied microscopically by Zirkel, 
it was found that we had never wrongly assigned a specimen to 
