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. 



Jlbdomen 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 Madrcpora 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 sent to this country." (England.) In the 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." 



