PLATE V. 



The specimens figured on this plate are now in the Illinois State Museum. They 

 were collected by Dr. Oliver Everett from the Trenton limestone near Dixon.IIl. 



PAGE 

 Fig. 1. CALATHIUM? LNFELIX U. & E 274 



1 and la. Two views of a worn specimen of this species. Natural size. 



Pig. 2. ZITTELELLA TYPICALIS var. SUBROTUNDA U. & E 269 



2 and 2a. Two views of a specimen showing the usual form of this variety. 



Natural size. 



Fig. 3 and 5. ZITTELELLA TYPICALIS U. & E 268 



3, Median vertical section, showing the cloacal tubes and the arrangement 

 of the radiating canals and capillary tubuli. Natural size. 



3 a. Portion of a thin vertical section, x!8, 

 3 b. Portion of a transverse section, x!8. 



3 o. Transverse section of cloaca! tubes, x 12. 



5 and 5 a. Two views of the best specimen seen. Natural size. 



Fig. 4. ZITTELELLA TY PIC ALIS var. PISTILLIFOKMIS U. & E 26!t 



Lateral view of a specimen of this variety, larger than usual. Natural 

 size. 



Fig. 6. ZITTELELLA INOSCULATA U. & E 271 



6. Polished upper surface of a large specimen. Natural size. 



6 a. Lateral view of another example. Natural size. 



Fig. 7. ZITTELELLA TYPICALIS var. TUKBINATA U. & E _'> 



and 7 a. Two views of a specimen of this variety. Natural size. 



