1088 The American Naturalist. [December, 
in the Hegau rocks. In a few of them the mineral is abundant in the 
usual form. In others it is only sparingly present, while in still others 
it is absent so far as could be learned. Consequently, the rocks fall 
into several classes. The Hohentwiel occurrences are of nosean-phon- 
olites, in which nosean is abundant in the groundmass and nepheline 
absent. The specimens from Mügdeberg and Schwindel are nosean- 
ophyres (corresponding to the leucitophyres), in which nosean and 
nepheline are both present. At Staufen, two types were found, one a 
leucite-phonolite, and: the other a true phonolite (nepheline-phonolite), 
The rock of Gonnersbohl is a hauyne-bearing trachyte or a trachytic 
phonolite. Each of these types is briefly described, and at the conclu- 
sion of the paper a few pages are devoted to an account of the tufa 
associated with them. 
The Rock of a New Island, off Pantelleria.—An island, 
measuring one kilo. in length, and two hundred metres in width, was. 
projected above the water off Pantelleria during the earthquake week 
beginning Oct. 14,- 1891. The new island is an aggregate of loose 
blocks and solid lava, whose characteristics have been described by 
Foerstner. The material in his possession was mainly a black. pumi- 
* Minn. u. Petrog. Mitth., XII, 1892, p. 510. 
ceous basalt of the composition : 
SiO, TiO, ALO, Fe,0, Feo MnO CaO MgO K,O Na,O H,O Total 
44.64 5.86 12.74 421 1117 .20 10.12 5.82 1.41 4,31 .51—100.99 
Attention is ealled to the large quantity of TiO, revealed by the analy- 
sis. Under the microscope the groundmass of the rock is seen to be a 
dark glass filled with highly colored microlites, and enclosing pheno- 
cysts of anorthite, olive-green augite, olivine and magnetite. The glass 
is sometimes in large quantity and at other times is present only in 
traces. The rock is a tachylitic basalt like that of Pantelleria and the 
other neighboring islands. 
Petrographical News.— The pyroxenite of Duerne, Dept. of the 
Rhone, France, is an aggregate of orthoclase, pyroxene, oligoclase, gar- 
net, and quartz. The structure of the rock varies from pegmatitic to 
granular. Its pyroxenie component is described by Gonnard? as light 
green in color, and as often possessing crystal outlines. It includes 
within its mass many crystals of sphene. Druses of vesuvianite line 
the walls of crevices in the rock, and galena is not an uncommon con- 
stituent of Bor veins traversing it. 
d. Min., XV, p. 232. 
