4. ON THE MODE OF OCCURRENCE AND THE
STRUCTURE AND DEVELOPMENT OF
TRIARTHRUS BECKI*


(Piate V1)


THE presence of antenne and other appendages on a trilo-
bite from the Utica Slate was announced in May, 1893,
by W. D. Matthew.t ‘The specimens were discovered by
W. S. Valiant, near Rome, New York, where they occur
in a fine-grained carbonaceous shale. It was apparent that
specimens preserving organs so delicate as antennz ought to
show, in addition, other anatomical features which would be
of great assistance in determining the zodlogical position of
the Trilobita. With this object in view, and with the assist-
ance of Professor Marsh, a collection was made for the Yale
University Museum. From this material it is hoped that
the remaining details in the structure of this important fossil
may be made out. The preliminary examination of the speci-
mens shows a number of new and remarkable structural
features, some of which will be briefly noticed here. It was
also possible for the writer to make observations in the field,
which furnish interesting facts as to the mode of occurrence
and to the habits of the trilobite.
* Abstract of a paper “On the Structure and Development of Trilobites,”
read before the National Academy of Sciences, November 8, 1893. American
Geologist, XIII, 38-43, pl. iii, 1894.
+ On Antennx and other Appendages of Triarthrus Beckii. Read before
the N. Y. Academy of Sciences, May, 1893. Published in Amer. Jour. Sci. (3),
XLVI, 121-125, August, 1893.
¢ Mr. Valiant informs me that he found the first specimen showing antenne
in 1884, but it was not until 1892 that other specimens were obtained by him
and M. Sid. Mitchell fully establishing the discovery. The specimens sent to
Columbia College were collected by W. S. Valiant, of Rutgers College.
