CRUSTACEA. 
81 
the cephala which agree in all respects with the originals of Lichas pustulosus, 
are the only parts of Lichas yet found at this locality. The pygidium represented 
on plate Ixxviii, fig. 7, of the Third Volume of the Palaeontology of New York, 
upon more careful scrutiny and removal of adhering rock, proves not to 
have the bilobed caudal margin as there illustrated, and its proper character is 
shown on plate xix, fig. 9; the margin bearing three pairs of lateral lobes, 
much narrower than in L. pustulosus, and terminating in a single, moderately 
broad posterior lobe. The single specimen showing this form of pygidium 
is from Schoharie, from which locality are also the large pygidia originally 
referred to Lichas pustulosus. 
The cephalic portions of Lichas Bigsbyi are known only from the Lower 
Pentamerus limestone at localities in Schoharie county. It is impossible, how¬ 
ever, to say which of the three different forms of pygidia represented on plate 
xix, fig. 9, plate Ixxvii, fig. 8 {op. cit.), plate Ixxviii, figs. 4, 5 {op. cit.), and plate 
xix A, fig. 1, is to be referred to this species. These cephala are not of uncom¬ 
mon occurrence, and by far the most abundant of the pygidia are those figured 
on the last two plates cited, the other two forms occurring, so far as known, 
only in single examples. It is therefore probable that the large pygidia bear¬ 
ing three pairs of lateral spines and a pair of posterior spines belong to the 
species Lichas Bigsbyi. 
[s.-G.] HOPLOLICHAS, Dames. 1877. 
Lichas (Hoplolichas) hylaeus, n. sp. 
PLATE XIX B, FIGS. 1, 2. 
The intra-sutural portion only of the cephalon has been observed. Outline 
semi-elliptical; surface strongly convex, tumid along the axial line, abruptly 
deflected to the margins. 
Glabella large, sub-pentagonal. Frontal lobe elongate-pyriform or clavate, 
widest and most convex anteriorly, narrowing and becoming depressed 
medially, and abruptly widening again at the occipital furrow. The second 
pair of transverse furrows is obsolete, the first and second pairs of glabellar 
