80 
PALEONTOLOGY OF NEW YORK. 
Petersb., 7th Ser., vol. xxxiii, No. 1, p. 42. 1886), to the sub-genus Cono- 
lichas, Dames, of which L. iriconica, Dames, and L. Schmidti, Dames, are the 
types In all the species enumerated by these authors, the third pair of lateral 
lobes is present in varying degrees of development. In L. Eriopis, however, 
it appears to be obsolete or represented only by a pair of tubercles; but as the 
general form of the head is the feature upon which the sub-genus is based, the 
obsolescence of these lobes will not vitiate the reference of the species to this 
group. 
Distribution. Upper Helderberg group. Corniferous limestone: Schoharie, 
Schoharie county; in the boulders of decomposed chert, Canandaigua, Ontario 
county. 
In order to correct, and to a certain degree, to complete the original determi¬ 
nations of the species of Lichas occurring in the Lower Helderberg formations, 
a few observations are here introduced. 
Lichas (Conolichas) pustulosus. 
PLATE XIX, FIGS. S, 10, 11. 
Lichas pustulosus. Hall. Pal. N. Y., vol. iii, p. 366, pi. Ixxvii, figs. 9, 10; pi. Ixxviii, figs. 1-3. 1859. 
Lichas (Conolichas) Bigsbyi. ? 
PLATE XIX A, FIG. 1. 
Lichas Bigsbyi, Hall. Pal. N. Y., vol. iii, p. 364, pl. Ixxvii, figs. 1-7 (8?); pi. Ixxviii, figs. 5, 6(?). 1859. 
Lichas (Conolichas ?), sp. ? 
PLATE XIX, FIG. 9. 
Lichas 2 ^'‘^t'>^losus, Hall. Pal. N. Y., vol. iii, pl. lxxviii,''%. 7. 1859. 
Recent careful investigations of the trilobitic layers of the shaly limestone in 
the vicinity of Clarksville, Albany county, have shown that the cephala of Lichas 
pustulosus are found in close association with pygidia quite distinct from those 
originally ascribed to that species. These bear broad, sub-lanceolate, recurved 
spines on the lateral margins in two pairs only; the posterior extremity 
terminating in a single broadly rounded lobe. This form of pygidium, and 
