CRUSTACEA. 
79 
slightly curved backward toward the apex, and in a single specimen, having 
a length equal to one-half the greatest width of the pygidium. The pleurae 
bear three double annulations, the anterior limb of each being small, the 
posterior broader and bearing on its most elevated portion a spine, similar in 
length and curvature to that upon the axis. The post-axial area is covered 
with scattered tubercles. Upon the margin, at the termination of each 
annulation, is a short, slender spine, making six on the sides, with two on 
the posterior limbus, and a very short inconspicuous lobe or spine at the 
termination of the axis. 
Surface Ornamentation. Upon the cephalon the surface of the glabella is 
covered with tubercles, which are fine and thickly set on the anterior 
portion of the frontal lobe, scattered and stronger on its more elevated 
portion, and a single pair near the summit of the posterior slope may have 
been spiniform ; toward the occipital furrow the tubercles become scattered 
and obsolete. The lateral lobes each bear a strong spiniform (?) tubercle 
near their most elevated point. Upon the cheeks the tubercles become acute 
and are arranged in rows parallel to the margins and the orbital node. The 
surface of these tubercles, of the genal spines, and of the cheek itself, 
between the spine-bases, is finely granulose. Upon the pygidium, besides 
the strong spines already described, are fine tubercles arranged regularly on 
the annulations and scattered without order over the post-axial area. 
Dimensions. An average specimen measures; 
, Cephalon. Pyg'idinm. 
Length_ 19 mm. 13 mm. 
Width_ 19 mm. (between the eyes.) 19 mm. 
A pygidium measuring 13 mm. in width bears a central spine 6.5 mm. long. 
Observations. The cephalon of this species, in the contour and elevation of 
the frontal and lateral lobes of the glabella, presents an agreement with the 
forms of Lichas referred by Dames (Zeitsch. d. deutsch. geol. Gesellsch, vol. 
xxix, p. 806. 1877), and Schmidt (Mem. de I’Acad. imp. d. Sciences d. St. 
