SWMSTEMATIC “PELROGRA PITY 373 
Class I. Earthy rocks (Roches terreuses). 
First family, feldspathic rocks (Roches feldspathiques). 
1. Order. _ Phaneromeric —of which the constituents are vis- 
ible to the naked eye (Phanérogénes dont les élé- 
ments sont visible a |’ceil nu). 
I. Genus. Aggregates (agrégées). 
Species: (1) harmophanite, (2) leptynite, (3) 
gneiss, (4) pegmatite, (5) granite, (6) syenite. 
2. Genus. Conglomerates (Conglomérées). 
Species: (1) feldspathic breccia, (2) feldspathic 
conglomerate, (3) feldspathic grit and sandstone. 
3. Genus. Unconsolidated sands, etc. (Meubles). 
Species: (1) Feldspathic sands and_ gravels 
(sables et graviers feldspathiques), (2) pebbles 
and débris of feldspathic rocks (galets et débris 
de roches feldspathiques). 
2. Order. Aphanitic—wholly or partially (Adélogénes en tout 
ou en partie —dont le volume des parties est en 
totalité ou en partie invisible). 
Other families of earthy rocks are named after pyroxene, 
amphibole, garnet, hypersthene, diallage, talc, mica, and quartz. 
An inconsequent element in the construction of the system, 
found in various places, is illustrated in the eleventh family, 
vitreous rocks, introducing a new factor while stating that the 
rocks in question are feldspathic. 
The great majority of known igneous rocks are assigned by 
this system to the aphanitic (adélogéne) orders of the various 
families, because their constitution is not wholly determinable 
by the naked eye. 
The system of Cordier was the system of France for years 
after his death, in 1861, and was published in elaborate form by 
D’Orbigny in 1868.* In all essential particulars the system had 
remained unchanged. At the beginning of the chapter upon the 
principles of classification is the declaration: ‘‘The description 
of rocks requires in advance: (1) the formation of species; (2) 
their classification” (La description des roches exige avant tout: 
1° linstitution des espéces; 2° leur classification). There is so 
*CHARLES D’ORBIGNY, Description des Roches, ete. Rédigé d’apreés la classifica- 
tion, les manuscrits inédits, et legons publiques de P. L. A. Cordier. Paris, 1868. 
