Head and fore abdomen very broad and depressed, the abdomen with ten
joints curved forwards at the undulations; post abdomen and tail with
about fifteen joints curved backwards at the undulations; the three
lobes of the tail more distinctly separated; divisions between the
joints of the abdomen double.
The representation of B. platycephala, figure 20, plate 2, of the
Geological Text Book, if it be accurately drawn, is certainly of a
trilobite never before described. On the buckler, which is without
eyes, there is delineated a figure, not unlike some of the leaves of
the mulberry tree.
The tail is also very peculiar. In Silliman's Journal, Volume 21st,
page 136, Professor Eaton proposed for this curious fossil the
temporary name of Ogygies latissimus. It is found, he observes, "in the
upper soft slaty variety of the rock which has been so successfully
used for the lias cement at Chitteningo, &c. Dr Smith, of Lockport,
(N. Y.) sent me two specimens, taken from a continuation of the
Chitteningo lias rock, immediately beneath the geodiferous lime rock
on which the cherty (cornitiferous) reposes." The whole animal is six
inches long, and three broad.
Nature of the Trilobite.
Every one familiar with the history of the Trilobites, is aware that
a good deal of controversy has existed among naturalists, respecting
the precise link in the grand chain of organized beings, these
singular fossil animals, should occupy. Professor Brongniart, Dr.
Dekay, Audoúin, and several other acute observers, have placed them
in the vicinity of the Limuli, and other Entomostraca with numerous
feet; while P. A. Latreille and others, presuming that these animals
were destitute of locomotive organs, as no vestige of them has ever
been discovered, fix their natural position in the neighbourhood of
the Chitones; or rather that they constituted the original stock of
the Articulata, being connected on the one hand with these latter
Mollusca, and on the other with those first mentioned, and even
with the Glomeris.[49] It was our original intention to have closed
this Monograph with a short history of these theories--and of the
notion advanced by Latreille and others, that the Trilobites have
been annihilated by some ancient revolution of our planet. All these
matters, we think, are now put to rest by the late discovery of some
living Trilobites in the southern seas, near the Falkland Islands. In
the cabinet of the Albany Institute, we have examined some of these
recent animals, which have very nearly the size and general appearance
of the Paradoxides Boltoni, as represented on our frontispiece; the
species cannot, however, belong to that genus, as the buckler is
furnished with eyes very similar to those of the Calymene Bufo; its
organs of locomotion are short, numerous, and concealed under the
shell--but I do not feel at liberty to notice the interesting animal
more minutely. It will probably be described and figured shortly, in
a perfectly full and satisfactory manner, by Dr. James Eights, the
enterprising discoverer, together with several other new and remarkable
genera and species belonging to the Entomostraca.
[Footnote 49: See Cuvier's Animal Kingdom, vol. iii. pp. 135-6.]