15 
all the trilobites are confined to an order of things 
before the present glorious creation.* — 
_ There appears to have been known to naturalists, 
when the improved edition of Prof. Brongniart’s work 
‘on the trilobites appeared in 1822, but 17 well mark- 
ed species, and out of which he constructed the five 
following genera, which he thus characterizes. 
Genus First. CALYMENE. 
Body capable of contraction into nearly a semi- 
_ cylindrical sphere. © : 
Buckler with many tubercles or folds. Two reticu- 
lated eye-shaped tubercles. 
Abdomen and Post-abdomen with entire edges. Ab- 
domen divided by 12 or 14 articulations. : 
No elongated tail. . 
* The incorrectness of the inference that all the genera and 
species of fossil animals found in the transition rocks must be 
now extinct, will appear from the following extract from Bake- 
well’s Geology :—‘ The Madrepora stylina, so common in transi- 
tion lime-stone rock, is entirely wanting in the secondary and 
tertiary strata, but a living animal of this species has been recent- 
ly discovered in the South Seas. The Pentacrinus makes its first 
distinct appearance in the lias; but is not frequently met with 
in the upper strata, and disappears entirely in the uppermost for- 
mations: hence it was long supposed that the species was ex- 
tinct. A living Pentacrinus has recently been discovered in the 
West Indies, and its stem and branches in a perfect state have 
been i country.’’ (England.) Inthe Museum at Alba- 
ny, N. Y., I have examined a recent Pentacrinus, which I con- 
clude, came from the West Indies, from the proprietor’s account 
of the manner in which he obtained it. It has been a very | 
perfect specimen—but the branches are gradually dropping off.” 
