142 Descriptions of two species of Trilobites. 
Paradoxides Becku. (Fig. 1.) 
Buckler bounded in front and laterally, by a nearly uniform curve 
scarcely exceeding a semicircle, distinctly convex: lateral lobes cu- 
neiform, broader posteriorly, gradually narrowing from behind for- 
ward, and passing into the narrow border which bounds the middle 
lobe anteriorly ; greatest width of each lateral lobe, about one half 
that of the middle lobe; width of each opposite the centre of the 
middle lobe, more than two thirds its greatest width: medial lobe 
somewhat broader than long, rounded posteriorly, convex ; sulci 
' deep and well defined, with the intermediate portions arched. 
The buckler of this species occurs abundantly in graywacke slate 
at the Cold Spring on the Erie Canal, eight miles east of Little Falls. 
‘This slate lies upon the lower transition limestone, of that part of 
the state. A small slab from this locality, scarce a foot long and 
two and a half inches wide, in the cabinet of this society, contains 
the remains and impressions of near forty specimens of the buckler. 
T have never met with a perfect abdomen in the Cold Spring slate, 
though specimens exhibiting a few articulations are common. 
have restored the original specific name of this species given it by 
Green, partially on account of its priority, but more especially be- 
cause of the inappropriateness of the specific name Triarthrus (three- 
jointed) applied by Harlan. This term, as employed to designate 
the genus by Green, who supposed that the buckler was the abdomen 
and tail, and three-jointed, was sufficiently appropriate. But with 
the present light on the subject, the buckler is very incorrectly de- 
scribed as “ triarthritic ;’ and moreover the existence of the sulci is 
a generic character. 
Paradoxides Eatoni. (Fig. 2.) 
Buckler convexly curved on the front margin, with a concave 
curvature laterally; nearly flat: lateral lobes broader posteriorly, 
greatest width about one half the breadth of the middle lobe; ab- 
ruptly diminishing in breadth and much less than half their greatest 
breadth opposite the centre of the middle lobe: middle lobe some- 
what longer than broad, nearly flat; sulci — with the interme- 
‘diate portions scarcely convex. 
This species is abundant in the anne slate in Turin, Utica, 
Fort Plain, and elsewhere i in ‘the state of New York. As Dr. _ 
dt Hiberty" of substituting the ie in boner of Prof, Eaton. 
