64 
_is the locality from which it is said to have odiniite 
rived. We ie nea 
As we have not been able to find anni detailed ac- 
count of this species, we have admitted both it and 
the genus to which it is said to belong into our Mo- 
nograph exclusively on the high authority of Profes- 
sor Brongniart, as quoted in the Manual of Geology. 
Weare not ignorant of the species of Trilobites found 
near Schenectady, and if permitted to offer a sugges- 
tion on this subject, it would be, that the description 
of the American ogygia, was made out by its distin- 
guished author from the fragment of an Isotelus, 
The Isotelus is not uncommon in that vicinity, and 
one of its extremities, might, even by a very close 
observer, be mistaken for that of an Ogygia—espe- 
cially by those who are not perfectly familiar with 
the Isotelus. | 
« 3 rete : , iy 
ce IsoTELus. Deka. ; ry 
This fine genus of trilobites was caiablehel fle | 
vember, 1824, by my friend James E. Dekay, M. D. 
It embraces a considerable number of species so. 
analogous to each other, that except in a very few 
cases, it is exceedingly difficult to point out their dis- 
tinctive characters. Some of the species of Tsotelus, 
appear to have reached a greater size than any other 
trilobite. In the cabinet of P. A. Browne, Esq., the: e 
is the fragment of one, which ie: been four- 
teen or fifteen inches Jong. | a 
- he. Isotelus is found in several pats of 
