_^ TKII.or.ITB8. 



The outer cheeks are abruptly convex below the eye, are there broadly grooved by a 

 furrow which widen- toward the margin, where it produces a rather deep emargina 

 tH MI of the periphery. Oenal extremities recurved, tapering to an acute angle, 

 I >ut not narrowed on the posterior surface. Occipital furrow broad and distinctly 

 defined. 



FIffft. 62, 93. Cranldlutn uf Aryet iretenbergriui*. var. jmulianut. x 3. 



The i-ephalon is covered with tubercles which are coarsest over the glabellar 

 lobes; on the cheeks they become scattered, vary more in size, and the coarser are 

 gathered along the posterior margin. No single specimen of the head retaining 

 all these parts in apposition has been observed, but in the cranidia the size is 

 about the same, an average glabella measuring 5 A mm. in length; 6| mm. between 

 the eyes. 



Of the thorax only a few scattered segments have been seen. 



Fig. 4. Pygldlum of a somewhat smaller Individual, x 3. 



Pygidinm short, transversely semielliptical in outline. The axis is convex and 

 has about one-third the width of the shield on its anterior margin. Its sides are 

 straight or slightly incurved, scarcely tapering, for about one-half the length of the 

 -hii-ld. Posteriorly it is broadly rounded and terminates in an elongated ridge 

 which extends to, and is confluent with the marginal thickening of the shield. Three 

 annulations are distinctly defined and behind these are one or more transverse rows 

 of tine tubercles. The pleura 1 are depressed convex, thickened about the margins. 

 There are two distinct pleura! ribs, the anterior being deeply sulcate and its two 

 divisions uniting to form a single narrow, acute, moderately long spine. The second 

 rib is also broadly sulcate, is much smaller than the first and its parts unite out- 

 wardly to form a second marginal spine longer than the first. Behind these two 

 ribs there are two tubercled spaces extending to the median prolongation of the 

 axis. On the margin, besides the first and second pairs of spines, there is a third or 

 terminal pair somewhat shorter than the others, and between them and the second 

 I'.nr is a small and short accessory pair, making in all eight short, rounded spines. 

 On the under side or doublure these are more flattened than above. 



Length of average specimens 4 mm.; anterior width 5 mm. 



