The references for the papers alluded to, all of them in the Journal, are as follows: Emerson, =24=, 195–202, 270–278, 349–359, 1882; ——, =23=, 302–308, 1882. Cross, =27=, 94–96, 1884; =31=, 432–438, 1886; =39=, 359–370, 1890; =41=, 466–475, 1891; =23=, 452–458, 1882. Iddings, =26=, 222–235, 1883; ——, =27=, 453–463, 1884; ——, =36=, 208–221, 1888; ——, =33=, 36–45, 1887. Williams, =31=, 26–41, 1886; =33=, 135–144, 191–199, 1887; =35=, 433–448, 1888; =36=, 254–259, 1888. ——, =34=, 137–145, 1887. Diller, =32=, 121–125, 1886; =37=, 219–220, 1889; ——, =33=, 45–50, 1887. Irving (=26=, 27–32, 321–322, =27=, 130–134, 1883; =29=, 358–359, 1885). Kemp (=35=, 331–332, 1888; =36=, 247–253, 1888; =38=, 130–134, 1889). Footnote 124: Zirkel, Lehrbuch der Petrographie, 2d ed., 1893. Footnote 125: Hunter and Rosenbusch, Ueber Monchiquit, etc., Min. petr. Mitth., =11=, 445, 1890. Rosenbusch, Ueber Structur und Class. der Eruptivgesteine, ibid., =12=, 351, 1891. Footnote 126: Iddings, Origin of Igneous Rocks, Bull. Phil, Soc. Washington, =12=, 89–213, 1892. Footnote 127: Brögger, Mineralien der Syenit-pegmatit-gànge, etc., Zs. Kryst., =16=, 1890. Footnote 128: ——, Basic Eruptive Rocks of Gran, Quart. Jour. Geol. Soc., =50=, 15, 1894; Grorudit-Tinguait-Serie, Vidensk. Skrift. 1 Math. nat. Kl., No. 4, 1894. Footnote 129: Weed and Pirsson, _e. g._ Shonkin Sag, the Journal, =12=, 1–17, 1901. Footnote 130: The references for the articles mentioned (all in the Journal) are as follows: Becker, =46=, 1893; =4=, 257, 1897; =3=, 21–40, 1897. Cross, =39=, 657–661, 1915. Adams, =22=, 95–123, 1906; =29=, 465–487, 1910. Daly, =22=, 195–216, 1906; =26=, 17–50, 1908. Wright, =22=, 224–230, 1906. Fenner, =29=, 217–234, 1910. Bowen, =39=, 175–191; =40=, 161–185, 1915. Pirsson, =50=, 116–121, 1895; =7=, 271–280, 1899. Smyth, =36=, 33–46, 1913. Murgoci, =20=, 133–145, 1905. Barrell, =13=, 279–296, 1902. Lindgren, =3=, 301–314, 1897; =9=, 269–282, 1900. Ransome, =5=, 355–375, 1898. Cross, =4=, 115–141, 1897. Hague, =1=, 445–457, 1896. Pogue, =28=, 218–238, 1909. Warren, =25=, 12–36, 1908. Goldman, =39=, 261–288, 1915. Washington and Pirsson, Belknap Mts., =20=, 344–353, 1905; =22=, 439–457, 493–515, 1906. ——, Red Hill, =23=, 257–276, 433–447, 1907. ——, Tripyramid Mt., =31=, 405–431, 1911. Footnote 131: Quantitative Classification of Igneous Rocks, Cross, Iddings, Pirsson and Washington, Chicago, 1903. Petrogenesis, C. Doelter, Braunschweig, 1906. Igneous Rocks, vols. =1= and =2=, J. P. Iddings, New York, 1909 and 1913. Problem of Volcanism, Iddings, New Haven, 1914. Natural History of Igneous Rocks, Alfred Harker, London, 1909.