154 The American Naturalist. (February, 
apophyses from laccolitic masses. It is a rock made up of phenocrysts 
of anorthoclase, sodalite and augite in a groundmass of lath-shaped 
feldspars and acicular aegirines and acmites imbedded in a colorless 
interstitial matter, composed in all probability of nepheline and anal- 
cite. The augite phenocrysts are provided with an outer zone of 
aegerine. Needles of this mineral are included in all the colorless 
constituents. The eleolite syenite is from the laccolites. It is panidio- 
morphic, with fresh onorthoclase phenocrysts in a fine grained mass of 
feldspar, augite, aegerine, acmite, the angular spaces between which 
are occupied by nepheline. Analyses of the syenite and of one variety 
of the trachyte gave: . 
SiO, Al,O, Fe,O, FeO MnO CaO MgO Na,O K,O TiO, P,O, Ign. Loss Total 
59.66 16.97 3.18 1.15 .19 232 .80 8.38 4.17 tr .14 2.53 .07 99.56 
62.17 18.58 215 105 tr- 157 73: 756.888 ti 1T “1.63.07 98.08 
Petrographical Notes.—In a glassy rock from near Harrismith, 
in the Orange Free States, Molengraff® finds small crystals of twinned 
cordierite, little octahedra of magnetite and skeleton crystals of augite. 
The cordierite is slightly pleochroic. Its crystals are well defined and 
possess all the peculiarities of the niijerak: An analysis of the rock 
shows: 
MO T a Al,O, Fe,O, FeO MgO CaO K,O Na,O Loss Total 
64.54 .T 19. 16 7.238 339 247 57 1.18 2.25—101.53 
The large percentage of SiO, present as compared with the small per- 
centages of the alkalies suggests to the author that the rock is an 
abnormal type. After a critical discussion of the literature of cordie- 
rite as a rock component, the conclusion is reached that, in all proba- 
bility, the specimens studied represent foreign inclusions fused in a 
basic rock. 
A very brief account of the lavas and ashes of the old volcano 
Rhobell Fawr near Dolgelley in Wales, is given us by Cole.’ The 
greater portion of the products are ashes containing hornblende and 
augite. The lavas are augite, aphanites and basaltic and andesitic 
andesites. 
5 Neues Jarb. f. Min. etc., 1894, I, p. 79. 
ê Geol. Magazine, x, 1893, p. 337. 
