li'J -' .31 ! 



PLATE XXIX. 



PAOE 



Fig. 1. PHACELOPOHA PEBTENUIS Ulr...:.':.-..'. 1 . 406 



1. A portion of;the zoarium. Natural size. 



1 a. Several segments, x 25. 



1 b. Vertical section, x 25. 



1 r. Transverse section showing relative size and position of the aperture, 



and the small lucid spot above, x 50. 



Top of Trenton or base of Cincinnati group, Alexander County,' 111. 



Illinois State Museum. 



Fig. 2. PHACELOPORArcONSTEICTA Ulr 406 



The type specimen natural size and magnified 25 times. 

 Tren'on limestone, Bu:g : n, Ky. E. O. Ulrioh. 



Fig. 3. PH YLLOPOBIN A GK ANISTBIATA Ulr 689 



3. An example showing reverse.Inat. size. 



3 <;. Portion of same, x 18, showing character of reverse. 



Top of Trenton, Alexander Co., 111. Illinois State Museum. 



Fig. 4." PBOTOCKISINA EXIGUA Ulr. (See also PI. LIII.) 405 



4. Two examples of the nat. size. 



4 a. Poriferous side, showing arrangement of apertmes and accessory 



poros, x 18, 



4 b. Non poriferous side, x 18. 

 4 p. Transverse section, x 18. 



Cincinnati group, Wilmington, III. Illinois State Museum. 



Fig. 5. HELOPOKA IMBMCATA Ulr 644 



Lower portion of a segment, x 18. 



Cincinnati group, Wilmington, III. Illinois State Museum. 



Fig. 5 . HELOPOBA FKAOILIS Hall. (See also flg. 18, in text,) (i43 



The ordinary appearance of a transverse section of this species. 

 Clinton group, Flamborough Head, Canada. 



Fig. 6. ABTHBOCLEMA ANGULABE Ulr 641 



6. One of the primary segments. Natural size, and x 12, 

 6 a and 6 b. The upper and lower extremities of or.e of the secondary seg- 

 ments, x 18. At the left of flg. 6n it is shown in natural size. 

 Cincinnati group, Wilmington, III. Illinois State Museum. 



Fig. 6 c. ABTHBOCLEMA PULCHELLUM Billings 64? 



A transverse section of a primary segment, x 18. At the upper side the 

 section passes through the "socket." 



