692 C. R. VAN HISE 
akero-syenite, if a new name is really necessary and preferable to 
augitic quartz-syenite. (2) The trachydolerites, designated by 
Washington as czmuinite, vulsinite, and toscanite,* may be called 
cimino-trachydolerite, vulsino-trachydolerite, and toscano - trachydo- 
lerite. Under this usage czmino, vulsino, and toscano, take the 
same place with reference to the trachydolerites, that hellefors, 
aasby, sirna, ottfdlls do to the diabases, as used by Rosenbusch 
(see p. —-). Indeed, Washington himself in one place speaks 
of pulaskite as pulaskitic syenite.? following the plan proposed this 
would be pudlasko-syenite. (3) As an illustration of the use of 
mineralogical terms compounded with names already com- 
pounded may be given augite-toscano-trachydolerite. If desirable, 
the order of the mineralogical and geographical parts of the 
name may be reversed. For instance, the leucite-trachytes, 
which Cross calls orendite and madupite,3 may be designated orendo- 
leucite-trachyte and madupo-leucite-trachyte. 
In all of these cases the geologist knows at once the general 
character of the rocks referred to.) In the frst casevhe knows 
the rocks are syenites; and, furthermore, that certain varieties 
of syenites are so abundant and so definite in character as to 
require a specific designation. In the second case he knows that 
there is a kind of rock intermediate between the trachytes and 
dolerites, and, if he knows what trachytes and dolerites are, he 
has a very clear conception of this rock without any further 
definition. He further knows that there are variations in the 
character of the trachydolerites which occur at particular locali- 
ties, and which, in the opinion of the author, are so abundant 
and distinctive as to require specific designations. In the third 
case he further knows at once from the name that certain varie- 
ties of the Toscano-trachydolerite contain augite; and infers 
that this variety is exceptional. He knows that the leucite- 
trachytes have variations which are thought to be of sufficient 
importance to require specific designation. 
t Jour. GEOL., Vol. V, pp. 350-361. 
2 Jour. GEOL., Vol. VI. p. 804. 
3 Igneous rocks of the Leucite Hills and Pilot Butte, Wyo., by WHITMAN Cross: 
Am. Jour. Sci., Vol. LV, 1897, pp. 138, 139. 
