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 pleura 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 p\ gidium 

 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, 121) mm. Fragments 

 of smaller individuals have also been found. A singh -mall thoracic seg- 

 ment measures 51 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 L35 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 



