Correspondence—S. J. Shand. 191 
one of the lines in the Shannon Basin, making six in all, have 
been deflected, five of them considerably and one through an angle 
of 45 degrees, so as profoundly to modify the interpretation. The 
two ‘‘ rather generalized ’’ have been generalized to such effect that 
the arrow which should pass down the east side of the Slieve Bloom 
Mountains is carried down the west. The figure on p. 190 shows 
Wright’s arrows by the full lines and Professor Gregory’s version by 
broken lines. The superposition was done by photographic pro- 
jections from a lantern slide in use here. 
These may seem small matters, but it would strike at the very 
root of our confidence in scientific statement of fact if an author were 
permitted without protest to take any liberties he might choose 
with the work of another author and describe the result as “ after 
W. B. Wright” or “ added from the map of Mr. Wright ”’. 
Percy F. KENDALL. 
Leeds. 
THE NOMENCLATURE OF PETROLOGY. 
Str,—Dr. Arthur Holmes, in his useful little book with the above 
title, disapproves of the term syenoid, which I have used as a con- 
traction of felspathoid-syenite, giving as his reason that the suffix 
-oid has been used in other senses, as in granitoid, trachytoid, 
pegmatoid (Evans), and dacitoid (Lacroix). The matter is a very 
trivial one, but in the present involved condition of petrographic 
nomenclature no proposal for simplification should be dismissed 
without fair consideration, and the very examples that Dr. Holmes 
quotes show that he has not considered the matter fully. Of the 
four terms that he quotes, the last two are of later introduction than 
mine, so that I might at least claim the right of priority. This is 
true, too, of Lacroix’s revival of “‘ basanitoid’’; and I cannot 
recall any other instance of a rock name in current use that ends in 
-oid. Then granitoid and trachytoid are adjectives, and should 
correctly be written granitoidal and trachytoidal, just like conchoidal 
and saccharoidal, But a more important consideration is just that 
every familiar suffix is used in various senses, and the ubiquitous 
-ite, for example, serves for rocks, minerals, fossils, meteorites, alloys, 
chemicals, official drugs, patent medicines, and a great variety of 
commercial products. I think, then, that Dr. Holmes’ objection 
is not a very well-reasoned one. 
The reason why it seems desirable to have a single word in place 
of the double-barrelled “ felspathoid-syenite”’ is pretty obvious. 
In the first place these rocks are quite as distinct from the syenites 
as are—let us say—the monzonites, and they have therefore an 
equal claim to a distinctive name. In the second place, nepheline- 
syenite is long enough already, and when further mineralogical 
qualifications have to be added the name becomes un- 
wieldy. A dreadful example of this is Dr. H. A. Brouwer’s 
* egirienamphiboolbiotietnepheliensyenietporphyr ’’. 
