196 DR. THOMAS STERRY HUNT ON THE 
order, according to Gümbel, first, the red or variegated gneiss, called by him Bojian, which 
is followed immediately by the newer grey or Hercynian gneiss, his second division, and 
by a third, the Hercynian mica-schist series, occasionally hornblendic. To this succeeds, 
in the fourth place, the Hercynian primitive clay-slate series, which is immediately overlaid 
by Lower Cambrian fossiliferous rocks. This primitive clay-slate series contains inter- 
stratified beds of limestone, sometimes dolomitic, attaining in places a thickness of 350 feet, 
and associated with siderite, which gives rise by epigenesis to valuable deposits of limonite 
along its outcrop. With these limestones are found varieties of hornblende and serpentine, 
accompanying which is the Lozoon Bavaricum of Gümbel. 
§ 84. The Hercynian gneiss is described by Gümbel as including much grey quartzose 
and micaceous gneiss, with frequent beds of dichroite-gneiss, granulite, serpentine, horn- 
blendic schists and crystalline limestones. With these are associated Eozoon Canadense, 
from which Giimbel supposed this upper gneissic series to represent the Laurentian, a view 
which was accepted by the present writer when, in 1866, he translated and edited Güm- 
sel’s paper * for the Canadian Naturalist, and has since been expressed by him elsewhere ; 
coupled with the suggestion that the Bojian might correspond to the Ottawa gneiss which 
underlies the Grenville series, the typical Laurentian (Lower Laurentian) of the Canadian 
survey. We are not, however, as yet prepared to recognize a sub-division in the older 
gneisses of continental Europe, and meanwhile the analogies between the great Hercynian 
gneiss and mica-schist series combined, and the younger gneisses and mica-schists of 
Saxony and of the Alps, lead us to refer what Giimbel has described as the newer gneiss 
series of Bodenmais and the Danube, to the same horizon as the younger gneisses of Gas-- 
taldi and Yon Hauer, the Montalban series; which in eastern Bavaria would seem, as in the 
Simplon, to rest directly upon the older gneiss, the Huronian being absent. The Hercy- 
nian clay-slate series, with its crystalline limestones, may correspond to the fourth group 
of the Alpine rocks, the argillo-talcose schists, which we have compared with the American 
Taconian. 
IV.—THE SERPENTINES OF ITALY. 
§ 85. Returning to the Italian Alps, we have now to call attention to a very important 
conclusion reached by Gastaldi with regard to the geographical relations of the pietre-verdi 
zone ; using the term in its larger sense as embracing all the newer crystalline rocks, or 
those above the ancient gneiss. In 1871, in the first part of his memoir on the Western 
Alps, he declared it as his opinion that “all the serpentinic masses of the Tuscan and 
Ligurian Apennines, and the serpentines, ophicalcites, saccharoidal limestones and granites 
of Calabria, are but a prolongation of this zone.” In this were included, as we have already 
seen, the Apuan Alps, and, farther westward, a large part of the Maritime Alps. In sup- 
port of these views he pointed out the mineralogical identity of the ophiolites and other 
crystalline rocks in the Alps and the Apennines. To the same horizon he also referred 
the so-called ophitic terrane of the Pyrennees. J 
§ 86. Gastaldi further called attention to the fact that ophiolitic rocks often appear in 
the form of isolated peaks or hills, for the reason that the accompanying crystalline schists 

* Giimbel, Ueber der Vorkommen yon Eozoon in dem Ostbayerischen Urgebirge, München Akad, Sitzungsb, 
1866. (I.) pp. 25-70; also Can. Naturalist, ili., 1868, pp. 81-101. 

