MIDDLE CAMBRIAN, AT STISSING, N. Y. 105 
defined tubercles, corresponding, apparently, with the 
scattered pits of the external surface. 
3. Kutorgina Stissingensis—Plate —, figs. 5, 6, 7 and 
8.—New species. Shell black, phosphatic; width slightly 
greater than the length, and, in most of the specimens 
collected, is about eight millimeters. General shape 
semi-circular. ‘The ventral valve has an elevated, pointed 
beak, from which the surface slopes down regularly 
toward the lateral margins, while in sloping down to the 
front margin it sometimes becomes concave centrally to 
the shell. Along the cardinal border of this valve, the 
shell is suddenly deflexed toward the hinge line, making 
a false area, separated centrally into two parts by a va- 
cant deltidial space. 
The dorsal valve is depressed and nearly flat, with a 
low beak. 
The surfaces of both valves are covered with very fine, 
sharp, concentric ridges, traversed by strie scarcely visi- 
ble to the naked eye. These surface markings are in- 
clined to run into minute undulations, and the effect of © 
this ornamentation, as viewed througha strong triplet, is 
often that of lovely basketwork. 
This exquisitely beautiful shell is allied to the well- 
known species, Kutorgina Labradorica. Imperfect frag- 
ments of it abound in these layers, and would easily be 
taken for fragments of Lingulepis pinniformis of the 
Potsdam. Close inspection will, however, reveal this 
distinction ; the concentric ridges or lamine of L. pin- 
niformis (at least as exhibited in Dutchess County, N. 
_Y.), are feebly defined, when magnified, and often run 
together obscurely ; while those of Kutorgina Stissing- 
ensis, as viewed with astrong triplet, are deeply cut, and 
generally individualized with exquisite perfection. 
4, Olenoides Stissingensis.—Plate —, figs 9-15.—New 
species. This trilobite is very important in determining 
the epoch of these strata, since it belongs to a genus 
55 
