Editorial Comment. 325 
the Belle Fourche. Hence it is nut impossible that Mato Tee- 
pee represents the deeper portions of what may have terminat- 
ed ori.c^inally by a pelelith like that of Martinique. 
The vertical basaltic cukunns seen in the plate turn outward 
all about their bases so as to terminate against the deeper inter- 
ior walls of the pipe in which they were originally enchased. 
This indicates not only that the plug at the time of its cooling 
was confined in a vertical pipe, but also that its heat escaped 
into its walls, but primarily toward the crater. The curved 
columns have successively fallen off, except near the base, leav- 
ing exposed to view only those which run upward in the central 
part of the mass without such curvature, or which curve out-, 
ward at greater depth. 
It is not necessary to multiply these illustrations of possible 
pelelitic roots. It is not intended to apply the new term to 
other rock masses than those that can be shown to have ascend- 
ed bodily above the crater rim of an active volcano; and to 
suggest that perhaps there are more than have been supposed 
of the same kind. 
[Note. — Since the foregoing was written professor 
I. C. RusseW, has published, in the American Journal 
of Science for April, 1904, a discussion of this subject, and has 
mentioned several other peaks in the United States that can 
be referred to this class, viz : the Panum crater, east of lake 
Mono, in California. This central column in the manner of its 
formation was understood by professor Russell, and was de- 
scribed by him in 1889 in the 8th x\nnual Report of the United 
States Geological Survey ; a crater near Pauline lake in the 
south-central part of Oregon. Professor Russell mentions, in 
his discussion, the criteria for distinguishing peleliths from 
volcanic necks and from erosion forms of igneous rocks.] 
REVIEW OF RECENT GEOLOGICAL 
LITERATURE. 
On the Structure of the Pterast>idae and Ccphalaspidac. By W. 
Patten {American Naturalist, vol. 37. no. 444. Dec. 1903). 
This paper i.s a new attempt to prove the* arachnid descent of the 
vertebrates. It is an argument in favor of two distinct propositions, — 
that the ostracoderms are the ancestors of the vertebrates and that 
the ostracoderms are derived from the arthropods. 
