334 Description of new North American Trilobites. 
at all. The Chululqui is thought to be nearly equal to the Saqui; 
and the Chelém to bear some resemblance to the Yashqui. The 
duration of the Sacqui, is limited at 10 or 15 years, and the biennial 
reproduction of plants from its roots, at eight or ten young plants; 
while the duration and reproduction of the Yashqui is only rated 
half as high. Here the people begin to be sensible of the value of 
their Henequin: and the first agricultural association ever formed in 
Yucatan, is a company for its cultivation. I impressed them with the 
opinion, that by it they would extract more wealth from the sandy 
and rocky surface of this peninsula, than from all the gold and silver 
mines of Mexico. I sarees respectfully, 
Henry Perrine. 
Arr. [X.—Descriptions of some new North American Trilobites ; 
by Jacos Green, M. D., Prof. of Chemistry i in Jeff. Med. Col- 
lege. 
Catymene? ODONTOCEPHALA.— Green. 
The outline of the buckler in this very remarkable species, is 
subtriangular. The front is separated from the cheeks by a deep 
groove on each side, its anterior edge is ornamented on each 
side by a kind of Etruscan border, composed of alternate projec- 
tions from the outer edge of the shell inwards, and from the inner 
portions of the shell outwards; the square protrusions on the one 
side, occupying intermediate square spaces on the other. ‘This 
singular and beautiful structure does not surround the anterior edge 
of the cheeks, but terminates at the separating furrow on each side. 
At the first glance, these projections in front, give to the trilobite the 
appearance of teeth. The surface of the front or middle portion 
of the buckler, is marked on each side near the oculiferous tubercles, 
with two deep pits producing several irregular pleats or folds, some- 
what like those on the front of Calymene Blumenbachii of Brong- 
niart. The cheeks are triangular in shape: their lateral edges are 
terminated by a plain raised hem, which corresponds in breadth with 
the ornamented border of the front. The oculiferous tubercles are 
very prominent, are almost encircled at their base by a deep groove, 
and have at their apices a semilunar depression. A shallow depres- 
sion also passes from behind each of the eyes, over the surface of 
the cheeks, nearly parallel with the furrow which separates them 
from the front. 
