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 heroine scattered 

 and obsolete. The lateral lobes each hear a strong spiniform ('.) tubercle 

 near their most elevated point. Upon the cheeks the tubercles become acute 

 and are arranged in rows parallel to the mar-ins and the orbital node. The 

 surface of these tubercles, of the genal spines, ami 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: 



' lephalon. Pygidium. 



Length 19 mm. 13 mm. 



Width 19 mm. (between the eyes.) L9 mm. 



A pygidium measuring 13 mm. in width hears 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 tie 

 forms of Lichas referred by Dames (Zeitsch. d. deutsch. geol. Gesellsch, vol. 

 xxix, p. 806. 1877), and Schmidt (Mem. de l'Acad. imp. d. Sciences d. St. 



