EXPLANATION OF PLATE XVII. 



Figures 1-5 ILLAENUS INSIGNIS Hall p. 215> 



1-3, Dorsal, anterior and lateral views of a nearly complete 

 cephalon. 4-5, Lateral and dorsal views of a nearly com- 

 plete pygidium. Both specimens from Hawthorn. (Pal. 

 Coll. Walker Museum, No. 9,902, Van Home Collection.) 



Figures 6-9 ILLAENOIDES TRILOBA n. sp p. 22(> 



(See also Plate XIX., Figs. 12-14.) 



6, Dorsal view of an incomplete specimen preserving the head, 

 thorax and pygidium from nearLemont. (Pal. Coll., Walker 

 Museum, No. 9,871, collected by L. H. Hyde). 7-9, Anterior, 

 dorsal and lateral views of a nearly complete cephalon, from 

 Bridgeport. (Pal. Coll. Walker Museum, No. 10,732. Van 

 Home Collection.) 



