362 
The American Geologist . 
June, 1896 
Figure 3 represents the trilobite restored, on the basis of the 
interpretation here given. 
Bohemilla may, therefore, be recognized as a synonym of 
JEglina , unless the lobation of the glabella and axis should be 
considered as of generic importance. This would be according 
a value to this feature greater than is recognized among the 
other species of JEglina which in this respect show equally 
great variations from the type, JE. rediviva. At any rate the 
bizarre appearance and remarkable characters ascribed to this 
trilobite are no longer matters of wonderment, and it is reduc¬ 
ed to the rank of an ordinary form. 
THE VOLCANIC TUFFS OF SEGALAS (ARIEGE). 
CONCLUSIONS TO BE DRAWN FROM THEIR 
STUDY ON THE SUBJECT OF THE ORI¬ 
GIN OF THE OPHITES. 
By A. Lacroix, Paris, Prance. 
The existence at Segalas of ophitic tuffs has recently been 
announced. Lacvivier has shown that they are older than 
the calcareous breccia of the lower Lias; Roussel has shown, 
besides, that they lie upon limestones of the horizon of Avic- 
ula contofta and that consequently they are contemporary 
with the close of the Rhetian. 
The purpose of this note is to show by the mineralogical 
study the clearly volcanic nature of these tuffs, and to draw 
from the results obtained some general conclusions on the ori¬ 
gin of the ophites of the Pyrenees. 
At Segalas the tuffs are seen lying between the Liassio brec¬ 
cia and the infra-Liassic limestones raised to vertically. I 
have collected in these tuffs fragments of quartzite with Avic- 
ula contofta , which leaves no doubt of their age. 
These tuffs present a remarkable*analogy with the basaltic 
tuffs of Auvergne. In the midst of a black mass, composed 
of little palagonitie fragments cemented by a little calcite, can 
be seen a considerable number of ejected blocks which reach 
the size of a man’s head; blocks of scoria, of compact lavas, 
cellular lavas, volcanic bombs with a central nucleus of a 
fragment of limestone, and numerous pieces of limestone. At 
certain points these blocks are distinctly stratified, and the 
tuff has evidently been worked over by water. It is but little 
