CRUSTACEA. 
75 
and the apex of the axis, are three linear, transverse furrows. The apex 
appears to have borne a strong, probably spiniform, tubercle. 
The pleum bear three broad, lobe-like annulations, which become obsolete 
before reaching the margin, and probably each one bears a conspicuous 
tubercle at its summit. They are strongly sulcate, the anterior limb being 
very narrow, and the posterior limb broad and inflated toward the margin. 
The post-axial area is elevated above the margin, though depressed below 
the pleurae and axis. The border is broad and bears a row of eight marginal 
spines, one at the termination of each of the three annulations, and two 
on the posterior limb. These spines are very long, increasing in length 
posteriorly, incurved towards the tips, and covered on the upper surface and 
the margins with narrow, acute spinules. The entire surface of the pygidium 
was covered with strong pustules, the larger of which appear to have been 
acute at the apex. A very small pygidium, which is referred with some 
doubt to this species, bears narrow annulations which extend to the margin, 
rendering the border obscure or obsolete. This feature may eventually 
prove to be of specific importance. The pygidium is known only from 
imperfect specimens, the most complete example showing nearly the entire 
under surface of the shield and portions of several of the spines. 
The type specimen of Lichas superbus, Billings, retains a large portion of 
the pygidium, and as this occurs in juxtaposition with a cephalon of Lichas 
grandis, little doubt can remain that the pygidia and cephala there described 
belonged to the same species. 
Dimensions. A very large fragment of a cephalon has the following dimen¬ 
sions ; length, 110 mm.; width between the eyes, 82 mm,; width along the 
occipital ring to the termination of the facial suture, 120 mm. Fragments 
of smaller individuals have also been found. A single small thoracic seg¬ 
ment measures 61 mm. transversely, and the spines on its axis are 10 mm. 
in length. A large pygidium has a length of 119 mm. to the apex of the 
posterior spines, and probably had a width of 135 mm., to the tips of the 
first lateral spines. The smallest pygidium observed is 18 mm in length. 
That the individuals of this species sometimes reached colossal dimensions 
