A PETROGRAPETCAIE SKsE Gr Ok, 42 GNA Aung) 
MEE EUAINVAS: 
PART III. 
Segregations —Before taking up the discussion of the chemical 
composition of the rocks described in Part IJ. it will be well to 
describe a series of segregations (endogenous enclosures) found 
in them, so that their chemical composition, which is closely 
related to that of the enclosing rocks, may be discussed at the 
same time with that of the latter. 
A few preliminary words may be allowed on the use of the 
term above given. The various forms of foreign matter that 
occur in rocks and minerals are of such common occurrence and 
so frequently referred to that the use of simple terms to denote 
the different occurrences seems advisable. Those suggested by 
Lacroix? seem to be the best possible, as well as consistent with 
the present usage of many petrographers. The term znclusion 
(Fr. zzclusion) is reserved for foreign bodies in the component 
minerals of a rock which are derived from the same magma as 
the including mineral; enclosure (Fr. enclave) denotes fragments 
of foreign rock in eruptives, e.g., such as have been torn away 
from the conduit walls; finally, segregation (Fr. ségrégation, Germ. 
NoTr.—As the writer was unable to revise the proofs some errors have crept into: 
the foregoing parts of this paper, and the following corrections must be made: 
II. 789, line 18; 806, lines 29, 31; 807, line 17; III. 44, line 3, for “ Kolautziki’”’ 
read “ Kolantziki.” 
II. 805, line 7, for ‘227-239 B.C.” read “ 276-239 B.C.” 
II. 812, line 27, for ‘von Lubach” vead ‘‘ von Seebach.”’ 
III. 38, line 31, after “‘ coast”? zzsert ‘of Methana.”’ 
III. 40, lines 7, 32, for “‘ Vesili” vead “‘ Vasili.” He Swe 
tContinued from page 46. 
?A, LACROIX: Sur les enclaves acides des roches volcaniques d’Auvergne. Bull. 
d. services de la carte geol. de la France. No. 11, 1890, pp. 25-56. Ref. in Neu. 
Jahrb., 1892, I.,-67. 
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