EXPLANATION OF PLATE XIX. 



Figures 1-6 ILLAENUS CUNICULUS Hall p. 219 



13, Dorsal, anterior and lateral views of a nearly complete 

 cranidium, from Wauwatosa, Wis. (Pal. Coll. Walker Museum 

 No. 10,730.) 4-6, Dorsal, lateral and anterior views of a 

 small but nearly complete cephalon, from Bridgeport. (Pal. 

 Coll. Walker Museum, No. 6,853, Gurley Collection.) 



Figures 7-11 ILLAENUS NIAGARENSIS Whitfield p. 219' 



78, Dorsal and lateral views of an incomplete specimen pre- 

 serving the head, thorax and pygidium. 9, Anterior view of 

 the same specimen, from Joliet. (Egan Collection, Chicago 

 Academy of Sciences.) 1011, Lateral and dorsal views of a 

 nearly complete pygidium, from Lockp'ort. (Pal. Coll. Walker 

 Museum, No. 10,731, Van Home Collection.) 



Figures 12-14 ILLAENOIDES TRILOBA n. sp p. 226 



(See also Plate XVII, Figs. 6-9.) 



12-13, Lateral and dorsal views of a large cranidium. (Pal. 

 Coll. Walker Museum. No. 9,897). 14, Dorsal view of a large 

 pygidium. Both specimens from near Lemont. (Pal. Coll. 

 Walker Museum, No. 9,872. Collected by L.H. Hyde.) 



