Merrill.] 
460 
[April 5, 
The other syenite, No. 153, I understand from Zirkel’s own 
words just quoted to be an unsatisfactory specimen of a genuine 
syenite. Indeed, his description of this specimen is to that 
effect. He says : “ A rock from the south of Pallisade Canon, 
Cortez Range, Nevada, should be mentioned (153), which seems 
macroscopically to be a porphyritic modification of the foregoing 
syenite.” 1 Here, as in other cases, 2 no one could possibly infer 
from Mr. Wadsworth’s remarks that Professor Zirkel had men- 
tioned the rock in any other than the most dogmatic way, 
wdiereas, in fact, it is clear that he alludes to a peculiar or modi- 
fied example in a sort of appendix fashion. It appeared to me 
that plagioclase prevailed decidedly over orthoclase in this rock, 
although many feldspars are so altered that it is impossible to de- 
termine their nature. On purely lithological grounds I should be 
likely to consider the rock a dioritic porphyrite. This, however, 
may be what Mr. Wadsworth means by “ old, altered andesite.” 
Under granites, in Zirkel’s Report, is a specimen from a 
granite dike, regarded by Mr. King as an exceptional occurrence 
in that district (specimen No. 77). Of this Mr. Wadsworth “sat- 
isfied himself that the section (1488) described by Zirkel never 
came from the hand specimen (1488), a not uncommon mistake, 
apparently, in Zirkel’s work on this collection.” 3 The thin 
section, No. 77, unquestionably corresponds to the hand 
specimen now bearing the collection number 21597. In the 
catalogue at the Museum opposite this coll, number stands the old 
coll, number 1488 quoted by Mr. Wadsworth, and I was moreover 
assured that this hand specimen formerly bore that number. The 
thin section, No. 77, had still the old label upon it with the num- 
ber 1488 underneath the new label. Besides the general similar- 
ity easily recognizable between the section and hand specimen, 
the quartzes in the section are impregnated with the black micro- 
lites mentioned by Zirkel, and a bit of the dark quartz broken off 
from the hand specimen was found, under the microscope, to be 
also full of such black microlites. 
Of the diabases (of the Report) mentioned by Mr. Wads- 
worth, Nos. 191, 192, 193, 194, 195 are considered by him to be 
1 Zirkel’s Report, p. 82. 
2 This paper, p. 457 and p. 469. 
3 These Proceedings, Vol. xxi, p. 256. 
